Conservation of Mechanical Energy Class 11 Notes, MCQs, Questions & Answers | CBSE & NEET

-  Dr Sanjay Kumar Pawar 

Conservation of Mechanical Energy Class 11 Physics Notes PDF | CBSE & NEET 

Conservation of Mechanical Energy explained with a falling ball showing the conversion of potential energy into kinetic energy.

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Link this page to related Class 11 Physics topics to improve SEO and user navigation:

1. Work, Energy and Power Class 11 Notes
2. Work-Energy Theorem Explained
3. Potential Energy Class 11 Notes
4. Kinetic Energy Formula and Examples
5. Conservative and Non-Conservative Forces
6. Gravitational Potential Energy Notes
7. Free Fall Motion Class 11
8. Laws of Motion Class 11
9. Newton's Laws of Motion Notes
10. Circular Motion Class 11 Notes
11. System of Particles and Rotational Motion
12. Gravitation Class 11 Notes
13. Mechanical Properties of Solids
14. Complete Class 11 Physics Notes Index 
15. Class 11 Physics MCQs with Answers
16. CBSE Class 11 Physics Important Questions
17. NEET Physics Chapter-wise Notes
18. NCERT Solutions for Class 11 Physics
19. Class 11 Physics Formula Sheet
20. Previous Year CBSE Class 11 Physics Questions

Chapter 5.8
Conservation of Mechanical Energy

Definition:
Mechanical Energy is the sum of Kinetic Energy (KE) and Potential Energy (PE).

Mechanical Energy = KE + PE

1. Work-Energy Theorem

Suppose a body moves through a small distance Δx under the action of force F. According to the Work-Energy Theorem,

ΔK = F(x) Δx

This means the work done by a force changes the kinetic energy of the body.

• Positive work increases kinetic energy.
• Negative work decreases kinetic energy.

2. Conservative Force

If the force is conservative, then potential energy can be defined.

−ΔU = F(x) Δx

The negative sign shows that whenever potential energy decreases, kinetic energy increases.

Example:
A falling stone loses potential energy and gains kinetic energy.

3. Combining the Equations

From the two equations:

ΔK = −ΔU

Therefore,

ΔK + ΔU = 0

or

Δ(K + U) = 0

4. Conservation of Mechanical Energy

Since Δ(K+U)=0, the total mechanical energy never changes.

K + U = Constant

This is called the Law of Conservation of Mechanical Energy.

5. Equation Between Two Positions

Ki + Ui = Kf + Uf

The total mechanical energy before motion equals the total mechanical energy after motion.

6. Conservative Force - Important Properties

• Potential energy can be defined.
• Work depends only on initial and final positions.
• Work does not depend on the path.
• Work done in a closed path is zero.
• Mechanical energy remains conserved.

7. Example - Falling Ball

A ball of mass m is dropped from height H. Initially the velocity is zero.

At Height H

PE = mgH

KE = 0

EH = mgH

At Height h

PE = mgh

KE = ½mv²h

Eh = mgh + ½mv²h

At Ground Level

PE = 0

KE = ½mv²f

E0 = ½mv²f

8. Conservation of Energy

EH = Eh = E0

Since only gravity acts on the body, mechanical energy remains constant.

mgH = mgh + ½mv²h = ½mv²f

9. Final Velocity

Using conservation of energy,

mgH = ½mv²f

After simplifying,

vf = √(2gH)

10. Velocity at Height h

mgH = mgh + ½mv²h

Therefore,

vh² = 2g(H − h)

11. Energy Conversion

Position	Potential Energy	Kinetic Energy
Top	Maximum	Zero
Middle	Decreasing	Increasing
Ground	Zero	Maximum

12. Important Points for NEET

• Mechanical Energy = KE + PE
• Gravity is a conservative force.
• Spring force is also conservative.
• Mechanical energy remains constant if only conservative forces act.
• Work done by a conservative force depends only on the initial and final positions.
• Work done in a closed path is zero.
• At the highest point, PE is maximum and KE is zero.
• At the ground, KE is maximum and PE is zero.
• Potential energy converts into kinetic energy during free fall.

13. Formula Sheet

Mechanical Energy = KE + PE

ΔK + ΔU = 0

K + U = Constant

Ki + Ui = Kf + Uf

PE = mgh

KE = ½mv²

vf = √(2gH)

vh² = 2g(H − h)

Work done in a Closed Path = 0

Prepared for NEET Physics Students • Chapter 5.8 - Conservation of Mechanical Energy

Conservation of Mechanical Energy

What is Mechanical Energy?

Mechanical Energy is the sum of Kinetic Energy (KE) and Potential Energy (PE).

Mechanical Energy = KE + PE

Work-Energy Theorem

When a force acts on an object, its kinetic energy changes.

ΔKE = Work Done

For conservative forces, Potential Energy decreases when Kinetic Energy increases.

ΔKE + ΔPE = 0

Energy Conversion During Falling

Top
PE Maximum
KE Zero

Middle
PE ↓
KE ↑

Ground
PE Zero
KE Maximum

Visual Falling Ball

⬇

As the ball falls, Potential Energy continuously converts into Kinetic Energy.

Example

Position	Potential Energy	Kinetic Energy	Total Energy
Top	100 J	0 J	100 J
Middle	60 J	40 J	100 J
Ground	0 J	100 J	100 J

Important Formulae

PE = mgh

KE = ½mv²

KE + PE = Constant

vf = √(2gH)

vh² = 2g(H − h)

NEET Remember:

• Gravity is a conservative force.
• Total Mechanical Energy remains constant if only conservative forces act.
• At the highest point: PE is maximum and KE is zero.
• At the ground: KE is maximum and PE is zero.
• Potential Energy converts into Kinetic Energy during falling.

CBSE Class 11 Physics

Chapter 5.8 - Conservation of Mechanical Energy

Question Bank with Answers

---

Part A - Multiple Choice Questions

1. Mechanical energy is the sum of

1. Potential energy and Heat energy
2. Kinetic energy and Potential energy
3. Heat energy and Electrical energy
4. Sound energy and Potential energy

Answer: B

2. Mechanical energy remains constant when

1. Friction acts
2. Air resistance acts
3. Only conservative forces act
4. External force acts

Answer: C

3. Which one is a conservative force?

1. Friction
2. Gravity
3. Air resistance
4. Viscous force

Answer: B

4. Work done by a conservative force depends on

1. Path followed
2. Distance travelled
3. Initial and final positions only
4. Speed

Answer: C

5. Work done in a closed path by gravity is

1. Positive
2. Negative
3. Zero
4. Infinite

Answer: C

---

Part B - Very Short Answer Questions

1. Define mechanical energy.

Answer: Mechanical energy is the sum of kinetic energy and potential energy.

2. Write the formula of mechanical energy.

Answer: E = KE + PE

3. Name one conservative force.

Answer: Gravitational force.

4. Write the formula of kinetic energy.

Answer: KE = ½mv²

5. Write the formula of potential energy.

Answer: PE = mgh

---

Part C - Short Answer Questions

1. What is conservation of mechanical energy?

Answer:
When only conservative forces act on a body, the total mechanical energy (kinetic energy + potential energy) remains constant throughout the motion.

2. What is a conservative force?

Answer:
A conservative force is a force whose work depends only on the initial and final positions and not on the path followed. Examples:

• Gravity
• Spring force

---

Part D - Long Answer Questions

1. State the law of conservation of mechanical energy.

Answer:
If only conservative forces act on a body, its total mechanical energy remains constant. Mechanical Energy = Kinetic Energy + Potential Energy Initial Energy Ki + Ui Final Energy Kf + Uf Therefore, Ki + Ui = Kf + Uf Example: A freely falling body loses potential energy and gains kinetic energy. The total mechanical energy remains constant.

---

Part E - Assertion and Reason

Assertion: Mechanical energy remains constant when only conservative forces act.

Reason: Gravity is a conservative force.

Answer: Both Assertion and Reason are true, and Reason is the correct explanation.

---

Part F - Fill in the Blanks

1. Mechanical energy is the sum of ______ and ______.
2. Gravity is a ______ force.
3. Potential energy converts into ______ during free fall.
4. Work done in a closed path is ______.
5. Mechanical energy remains ______ when only conservative forces act.

Answers:

1. Kinetic energy, Potential energy
2. Conservative
3. Kinetic energy
4. Zero
5. Constant

---

Part G - Match the Columns

Column A	Column B
Gravity	Conservative force
Friction	Non-conservative force
Potential Energy	mgh
Kinetic Energy	½mv²

Matching Answers 1 → Conservative force 2 → Non-conservative force 3 → mgh 4 → ½mv²

---

Part H - Case Study

A ball of mass 2 kg is dropped from a height of 20 m. Ignore air resistance.

Q1. Which energy is maximum at the top?

Answer: Potential Energy

Q2. Which energy is maximum at the ground?

Answer: Kinetic Energy

Q3. Calculate total mechanical energy at the top. Take g = 10 m/s².

PE = mgh = 2 × 10 × 20 = 400 J Answer = 400 Joule

Q4. Is mechanical energy conserved?

Yes. Only gravity acts.

---

Important Formulae

• E = KE + PE
• KE = ½mv²
• PE = mgh
• Ki + Ui = Kf + Uf
• Δ(KE + PE) = 0
• v = √(2gH)
• v² = 2g(H − h)
• Work in closed path = 0

---

End of CBSE Class 11 Physics Question Bank

The Concept of Potential Energy Notes for NEET 2026 | Class 11 Physics Chapter 5.7

 - Dr.Sanjaykumar Pawar 

Gravitational Potential Energy Notes for NEET with Formula & Examples

Gravitational Potential Energy (PE = mgh) and its conversion into kinetic energy explained with simple examples for NEET students.

Internal Links

Work, Energy and Power Complete Notes

Kinetic Energy Formula and Derivation

Work Done by a Constant Force

Conservative and Non-Conservative Forces

Law of Conservation of Mechanical Energy

Power in Physics Notes

Motion in a Straight Line Notes

Newton's Laws of Motion Notes

Gravitation Complete Notes

Acceleration Due to Gravity (g) Notes

Escape Velocity Notes

Circular Motion Notes

Mechanical Properties of Solids

Rotational Motion Notes

Oscillations and Simple Harmonic Motion

NEET Physics Formula Handbook

Class 11 Physics Chapter-wise Notes

Most Important NEET Physics MCQs

Previous Year NEET Physics Questions

NCERT Physics Chapter 5 Summary

NEET Physics Notes

Chapter 5.7 – The Concept of Potential Energy

---

1. Meaning of Potential Energy

The word Potential means the ability or capacity to do work in the future.

Potential Energy (PE) is the energy stored in a body because of its position or shape (configuration).

Definition

Potential Energy is the energy possessed by a body due to its position or configuration.

---

2. Everyday Examples

Example 1 – Stretched Bow

• A stretched bow stores energy.
• When the string is released, stored energy changes into kinetic energy.
• The arrow moves with high speed.

Example 2 – Earthquake

• The Earth's crust has cracks called fault lines.
• These fault lines store a large amount of energy.
• When they suddenly move, the stored energy is released.
• This causes an earthquake.

Potential Energy is stored energy that can later change into kinetic energy.

---

3. Gravitational Potential Energy

Consider a ball of mass m near the Earth's surface.

Assumption

• Acceleration due to gravity (g) remains constant.
• Height (h) is much smaller than Earth's radius.

\[ h \ll R_E \]

Where

• h = height of object
• R_E = radius of Earth

---

4. Raising a Ball

Suppose a ball is lifted upward through height h.

• Gravity acts downward.
• An external force is required to lift the ball.
• Work is done against gravity.

\[ W = mgh \]

This work gets stored as gravitational potential energy.

---

5. Formula of Gravitational Potential Energy

\[ PE = V(h)=mgh \]

Where

• m = mass
• g = acceleration due to gravity
• h = height

---

6. Important Points

• Greater height → Greater Potential Energy.
• Greater mass → Greater Potential Energy.
• If h = 0, then Potential Energy = 0.

---

7. Relation Between Force and Potential Energy

\[ F=-\frac{dV}{dh} \]

Since

\[ V=mgh \]

Differentiate,

\[ \frac{dV}{dh}=mg \]

Therefore,

\[ F=-mg \]

The negative sign shows that gravity always acts downward.

---

8. Conversion of Potential Energy into Kinetic Energy

When the ball is released:

• Potential Energy decreases.
• Kinetic Energy increases.
• At the ground, Potential Energy becomes minimum.
• Kinetic Energy becomes maximum.

---

9. Speed of Falling Ball

Using the equation of motion,

\[ v^2=u^2+2gh \]

Since

\[ u=0 \]

Therefore,

\[ v^2=2gh \]

---

10. Kinetic Energy at Ground

\[ KE=\frac12 mv^2 \]

Substitute

\[ v^2=2gh \]

\[ KE=\frac12 m(2gh) \]

\[ KE=mgh \]

Hence,

\[ PE=KE \]

---

11. When Does Potential Energy Exist?

Potential Energy exists only for Conservative Forces.

Examples

• Gravitational Force
• Spring Force
• Electrostatic Force

---

12. Conservative Force

A Conservative Force is a force whose work depends only on the initial and final positions and not on the path followed.

Examples

• Gravity
• Spring Force
• Electrostatic Force

---

13. Mathematical Definition

\[ F(x)=-\frac{dV}{dx} \]

Potential Energy exists only if the force satisfies this equation.

---

14. Work Done by Conservative Force

\[ \int_{x_i}^{x_f}F(x)\,dx =-(V_f-V_i) \]

or

\[ W=V_i-V_f \]

Meaning:

Work done by a conservative force equals the decrease in Potential Energy.

---

15. Change in Potential Energy

\[ \Delta V=-W \]

Meaning

• If gravity does positive work, Potential Energy decreases.
• If work is done against gravity, Potential Energy increases.

---

16. Inclined Plane Example

A body slides from the top of a smooth inclined plane of height h.

Its speed at the bottom is

\[ v=\sqrt{2gh} \]

This speed depends only on height and not on the angle of inclination.

---

17. Kinetic Energy at Bottom

\[ KE=\frac12 mv^2 \]

Substitute

\[ v^2=2gh \]

\[ KE=mgh \]

Hence,

Loss of Potential Energy = Gain of Kinetic Energy

---

18. Non-Conservative Force

A Non-Conservative Force is a force whose work depends on the path followed.

Examples

• Friction
• Air Resistance
• Viscous Force

---

19. Dimensions of Potential Energy

\[ [ML^2T^{-2}] \]

---

20. SI Unit

Joule (J)

---

21. Energy Conversion

Potential Energy can convert into

• Kinetic Energy
• Heat Energy
• Sound Energy

---

22. Important NEET Formula Sheet

Formula	Expression
Gravitational Potential Energy	\(PE=mgh\)
Force and Potential Energy	\(F=-\frac{dV}{dh}\)
General Relation	\(F=-\frac{dV}{dx}\)
Work Done	\(W=V_i-V_f\)
Change in Potential Energy	\(\Delta V=-W\)
Speed of Falling Body	\(v=\sqrt{2gh}\)
Kinetic Energy	\(KE=\frac12 mv^2\)
At Ground	\(KE=mgh\)

---

23. NEET One-Line Revision

• Potential Energy is stored energy.
• It depends on position or configuration.
• Gravitational Potential Energy = mgh.
• Gravity is a conservative force.
• \(F=-\frac{dV}{dx}\)
• \(\Delta V=-W\)
• Potential Energy decreases when gravity does work.
• Potential Energy converts into Kinetic Energy during free fall.
• On a frictionless inclined plane, speed depends only on height.
• SI Unit = Joule (J).
• Dimensions = \([ML^2T^{-2}]\)
• Mechanical Energy remains conserved when only conservative forces act.

End of Chapter 5.7 – The Concept of Potential Energy

CBSE Class 11 Physics

Chapter 5.7 – The Concept of Potential Energy

Part 1 : MCQs & Very Short Answer Questions

Section A : Multiple Choice Questions (MCQs)

1. Potential energy is the energy possessed by a body due to its:

1. Speed
2. Mass
3. Position or configuration
4. Temperature

Answer: (c) Position or configuration

2. The SI unit of potential energy is:

1. Newton
2. Joule
3. Watt
4. Pascal

Answer: (b) Joule

3. Gravitational potential energy of a body is:

1. mg
2. gh
3. mgh
4. mv²

Answer: (c) mgh

4. The dimensional formula of potential energy is:

1. [MLT⁻²]
2. [ML²T⁻²]
3. [ML²T⁻¹]
4. [MLT]

Answer: (b) [ML²T⁻²]

5. Potential energy depends upon:

1. Speed
2. Position or configuration
3. Momentum
4. Temperature

Answer: (b) Position or configuration

6. Which of the following is a conservative force?

1. Friction
2. Air resistance
3. Gravity
4. Viscous force

Answer: (c) Gravity

7. The relation between force and potential energy is:

1. F = dV/dx
2. F = –dV/dx
3. F = V/x
4. F = Vx

Answer: (b) F = –dV/dx

8. If the height of an object is doubled, its gravitational potential energy becomes:

1. Half
2. Double
3. Four times
4. Zero

Answer: (b) Double

9. At ground level, the potential energy is generally taken as:

1. Infinity
2. mgh
3. Zero
4. mg

Answer: (c) Zero

10. During free fall:

1. Potential energy increases
2. Kinetic energy decreases
3. Potential energy converts into kinetic energy
4. Both energies remain constant

Answer: (c) Potential energy converts into kinetic energy

Section B : Very Short Answer Questions (1 Mark)

1. Define potential energy.

Potential energy is the energy possessed by a body due to its position or configuration.

2. Write the SI unit of potential energy.

Joule (J)

3. Write the dimensional formula of potential energy.

[ML²T⁻²]

4. Write the formula of gravitational potential energy.

PE = mgh

5. What is a conservative force?

A conservative force is a force whose work depends only on the initial and final positions and not on the path followed.

6. Name one conservative force.

Gravitational force.

7. Name one non-conservative force.

Frictional force.

8. Write the relation between force and potential energy.

F = –dV/dx

9. What is gravitational potential energy?

It is the energy possessed by a body due to its position above the Earth's surface.

10. What happens to potential energy during free fall?

Potential energy decreases and converts into kinetic energy.

11. Write the expression for kinetic energy.

KE = ½mv²

12. State the law of conservation of mechanical energy.

When only conservative forces act on a body, the total mechanical energy (Potential Energy + Kinetic Energy) remains constant.

13. Give one example of stored energy.

A stretched spring or a stretched bow.

14. Does potential energy depend upon velocity?

No. It depends only on position or configuration.

15. Write the mathematical relation for change in potential energy.

ΔV = –W

End of Part 1
Next: Part 2 – Short Answer & Long Answer Questions

CBSE Class 11 Physics

Chapter 5.7 – The Concept of Potential Energy

Part 2 : Short Answer & Long Answer Questions

Section C : Short Answer Questions (2–3 Marks)

1. Define potential energy. Explain with one example.

Potential energy is the energy possessed by a body due to its position or configuration. Example: A stretched bow stores potential energy. When the string is released, the stored potential energy changes into kinetic energy and the arrow moves with high speed.

2. Derive the expression for gravitational potential energy.

Consider a body of mass m lifted vertically through a height h. Weight of body = mg Work done against gravity

W = Force × Distance

W = mg × h

W = mgh

This work is stored as gravitational potential energy. Therefore,

PE = mgh

3. Why is gravitational force called a conservative force?

Gravitational force is called a conservative force because:

• Its work depends only on the initial and final positions.
• It does not depend on the path followed.
• Mechanical energy remains conserved when only gravity acts.

4. What happens to potential energy during free fall?

During free fall:

• Potential energy decreases.
• Kinetic energy increases.
• Total mechanical energy remains constant.

Thus, potential energy is converted into kinetic energy.

5. Differentiate between conservative and non-conservative forces.

Conservative Force	Non-Conservative Force
Work depends only on initial and final positions.	Work depends on the path followed.
Mechanical energy is conserved.	Mechanical energy is not conserved.
Example: Gravity	Example: Friction

6. Explain the relation between force and potential energy.

For a conservative force,

\[ F=-\frac{dV}{dx} \]

The negative sign shows that the force acts in the direction of decreasing potential energy.

Section D : Long Answer Questions (5 Marks)

1. Explain gravitational potential energy and derive its formula.

Potential energy is the stored energy possessed by a body because of its position. Suppose a body of mass m is lifted vertically upward through height h. Weight of the body

Force = mg

Work done

W = Force × Distance

W = mg × h

W = mgh

Since this work is stored as energy,

PE = mgh

Where

• m = Mass of the body
• g = Acceleration due to gravity
• h = Height above the ground

Therefore,

Gravitational Potential Energy = mgh

2. Explain how potential energy converts into kinetic energy during free fall.

Consider a body kept at a height h. Initially,

Potential Energy = mgh

When the body is released,

• Potential energy decreases.
• Kinetic energy increases.
• Total mechanical energy remains constant.

Using the equation of motion,

\[ v^2=2gh \]

Kinetic energy,

\[ KE=\frac12 mv^2 \]

Substituting,

\[ KE=\frac12 m(2gh) \]

\[ KE=mgh \]

Hence,

Potential Energy = Kinetic Energy

This proves the conservation of mechanical energy.

3. Explain the law of conservation of mechanical energy.

The law states: "When only conservative forces act on a body, the total mechanical energy remains constant." Mechanical Energy

Mechanical Energy = Potential Energy + Kinetic Energy

During free fall,

• Potential energy decreases.
• Kinetic energy increases.
• The total remains constant.

Therefore,

PE + KE = Constant

This is known as the law of conservation of mechanical energy.

4. A body of mass 5 kg is lifted to a height of 10 m. Calculate its gravitational potential energy. (Take g = 9.8 m/s²)

Given:

• Mass (m) = 5 kg
• Height (h) = 10 m
• g = 9.8 m/s²

Formula

PE = mgh

Calculation

PE = 5 × 9.8 × 10

PE = 490 J

Answer: The gravitational potential energy is 490 J.

5. State any five characteristics of potential energy.

1. Potential energy is stored energy.
2. It depends on position or configuration.
3. Its SI unit is Joule (J).
4. Its dimensional formula is [ML²T⁻²].
5. It can be converted into kinetic energy.

End of Part 2
Next: Part 3 – Assertion & Reason, Fill in the Blanks, Statement-Based Questions

CBSE Class 11 Physics

Chapter 5.7 – The Concept of Potential Energy

Part 3 : Assertion & Reason, Fill in the Blanks, Statement-Based Questions

Section E : Assertion and Reason Questions

Question 1

Assertion (A): Gravity is a conservative force.

Reason (R): Work done by gravity depends only on the initial and final positions.

Answer:
✔ Assertion is True.
✔ Reason is True.
✔ Reason is the correct explanation of the Assertion.

Question 2

Assertion (A): Potential energy decreases during free fall.

Reason (R): Kinetic energy increases during free fall.

Answer:
✔ Assertion is True.
✔ Reason is True.
✔ Reason correctly explains the Assertion.

Question 3

Assertion (A): Friction is a conservative force.

Reason (R): Work done by friction depends upon the path followed.

Answer:
✘ Assertion is False.
✔ Reason is True.

Question 4

Assertion (A): SI unit of potential energy is Joule.

Reason (R): Potential energy is a form of energy and work.

Answer:
✔ Assertion is True.
✔ Reason is True.
✔ Reason correctly explains the Assertion.

Question 5

Assertion (A): Potential energy depends upon velocity.

Reason (R): Potential energy depends upon position.

Answer:
✘ Assertion is False.
✔ Reason is True.

Section F : Fill in the Blanks

1. Potential energy depends upon the __________ of the body.

Answer: Position

2. The SI unit of potential energy is __________.

Answer: Joule (J)

3. Gravitational potential energy is equal to __________.

Answer: mgh

4. Gravity is a __________ force.

Answer: Conservative

5. Friction is a __________ force.

Answer: Non-conservative

6. During free fall, potential energy converts into __________ energy.

Answer: Kinetic

7. The dimensions of potential energy are __________.

Answer: [ML²T⁻²]

8. The relation between force and potential energy is __________.

Answer: F = −dV/dx

9. Potential energy is also called __________ energy.

Answer: Stored

10. Mechanical energy remains constant when only __________ forces act.

Answer: Conservative

Section G : Statement-Based Questions (True / False)

State whether the following statements are True or False.

1. Potential energy depends upon position.
Answer: True
2. Friction is a conservative force.
Answer: False
3. SI unit of potential energy is Joule.
Answer: True
4. Potential energy can be converted into kinetic energy.
Answer: True
5. Gravity is a conservative force.
Answer: True
6. Potential energy depends upon velocity.
Answer: False
7. Mechanical energy is conserved when only conservative forces act.
Answer: True
8. The dimensional formula of potential energy is [ML²T⁻²].
Answer: True
9. Potential energy is measured in Newton.
Answer: False
10. A stretched spring possesses potential energy.
Answer: True

Section H : Formula-Based Questions

1. Write the formula of gravitational potential energy.

PE = mgh

2. Write the relation between force and potential energy.

F = −dV/dx

3. Write the formula for change in potential energy.

ΔV = −W

4. Write the formula of kinetic energy.

KE = ½mv²

5. Write the speed of a freely falling body from height h.

v = √(2gh)

End of Part 3

Next: Part 4 – Case Study, Match the Columns, Competency-Based Questions & HOTS

CBSE Class 11 Physics

Chapter 5.7 – The Concept of Potential Energy

Part 4 : Case Study, Match the Columns, Competency-Based Questions & HOTS

Section I : Case Study Questions

Case Study

A ball of mass 2 kg is lifted vertically to a height of 10 m. It is then released and falls freely under gravity. Take g = 9.8 m/s². Answer the following questions.

1. What type of energy does the ball possess at the highest point?

Potential Energy.

2. Calculate the gravitational potential energy of the ball.

Given:
Mass = 2 kg
Height = 10 m
g = 9.8 m/s²

PE = mgh
= 2 × 9.8 × 10
= 196 J

Answer: 196 J

3. What happens to the potential energy during free fall?

Potential energy decreases continuously.

4. Which form of energy increases during free fall?

Kinetic Energy.

5. Which law is verified in this example?

Law of Conservation of Mechanical Energy.

Section J : Match the Columns

Column A	Column B
1. Potential Energy	A. Joule
2. Kinetic Energy	B. Energy of Motion
3. Gravity	C. Conservative Force
4. Friction	D. Non-Conservative Force
5. SI Unit of Potential Energy	E. Stored Energy

Correct Matching

Column A	Column B
1	E
2	B
3	C
4	D
5	A

Section K : Competency-Based Questions

1. Why does a book kept on a table possess potential energy?

Because it is at a height above the ground and has the ability to do work if allowed to fall.

2. Why is no work done in moving a body horizontally on a frictionless surface?

Because the height of the body does not change. Therefore, gravitational potential energy remains constant.

3. Why does a stretched spring possess potential energy?

Because energy is stored due to the change in its shape (configuration).

4. Why does an object gain kinetic energy while falling?

Because its gravitational potential energy is converted into kinetic energy during free fall.

5. Why is gravity considered a conservative force?

Because the work done by gravity depends only on the initial and final positions, not on the path followed.

Section L : HOTS (Higher Order Thinking Skills)

1. Can a body have potential energy even when it is at rest? Explain.

Yes. A body at rest can possess potential energy due to its position or configuration. For example, a book placed on a shelf has gravitational potential energy.

2. Why does the speed of a body at the bottom of a smooth inclined plane not depend on the angle of inclination?

Because the loss of potential energy depends only on the vertical height. Hence, the final kinetic energy and speed depend only on height, not on the angle of inclination.

3. Explain why friction cannot store potential energy.

Friction is a non-conservative force. The work done against friction is converted into heat and sound energy instead of being stored as potential energy.

4. A body is lifted to two different heights. At which height will its potential energy be greater? Why?

The potential energy will be greater at the larger height because gravitational potential energy is directly proportional to height (PE = mgh).

5. Give one practical example showing the conversion of potential energy into kinetic energy.

A roller coaster at the top of a track has maximum potential energy. As it moves downward, its potential energy is converted into kinetic energy, increasing its speed.

Section M : Extra Practice Questions

1. State the principle of conservation of mechanical energy.
2. Write any two examples of conservative forces.
3. Write any two examples of non-conservative forces.
4. Explain why potential energy is called stored energy.
5. Write the SI unit and dimensional formula of potential energy.

Answers:

1. Total mechanical energy remains constant when only conservative forces act.
2. Gravitational force and spring force.
3. Frictional force and air resistance.
4. Because it is stored due to position or configuration and can later convert into kinetic energy.
5. SI Unit: Joule (J), Dimensional Formula: [ML²T⁻²]

✅ End of Complete CBSE Class 11 Physics Question Bank
Chapter 5.7 – The Concept of Potential Energy

Includes:

• ✔ MCQs
• ✔ Very Short Answer Questions
• ✔ Short Answer Questions
• ✔ Long Answer Questions
• ✔ Assertion & Reason
• ✔ Fill in the Blanks
• ✔ Statement-Based Questions
• ✔ Case Study Questions
• ✔ Match the Columns
• ✔ Competency-Based Questions
• ✔ HOTS Questions