- Dr.Sanjaykumar Pawar
CBSE & NEET Physics Unit Conversion Notes, Tricks, MCQs & Shortcuts
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| NEET Physics Unit Conversion Chart with formulas, shortcuts, and memory tricks for fast exam revision. |
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Unit Conversion in Physics (CBSE Class 11)
1.2 Fill in the blanks by suitable conversion of units
(a) 1 kg m² s⁻² = ______ g cm² s⁻²
Step 1: 1 kg = 10³ g
Step 2: 1 m² = (10² cm)² = 10⁴ cm²
Step 3: Multiply
= 10³ × 10⁴ g cm² s⁻²
= 10⁷ g cm² s⁻²
Step 2: 1 m² = (10² cm)² = 10⁴ cm²
Step 3: Multiply
= 10³ × 10⁴ g cm² s⁻²
= 10⁷ g cm² s⁻²
(b) 1 m = ______ ly
1 light year = 9.46 × 10¹⁵ m
1 m = 1 / (9.46 × 10¹⁵) ly
= 1.06 × 10⁻¹⁶ ly
1 m = 1 / (9.46 × 10¹⁵) ly
= 1.06 × 10⁻¹⁶ ly
(c) 3.0 m s⁻² = ______ km h⁻²
Step 1: 1 m = 10⁻³ km → 3.0 m s⁻² = 3.0 × 10⁻³ km s⁻²
Step 2: 1 s⁻² = (3600)² h⁻² = 1.296 × 10⁷ h⁻²
Step 3: Multiply
= 3.0 × 10⁻³ × 1.296 × 10⁷
= 3.89 × 10⁴ km h⁻²
Step 2: 1 s⁻² = (3600)² h⁻² = 1.296 × 10⁷ h⁻²
Step 3: Multiply
= 3.0 × 10⁻³ × 1.296 × 10⁷
= 3.89 × 10⁴ km h⁻²
(d) G = 6.67 × 10⁻¹¹ N m² kg⁻² = ______ cm³ s⁻² g⁻¹
1 N = 1 kg m s⁻²
So, N m² kg⁻² = m³ s⁻² kg⁻¹
Convert units:
1 m³ = 10⁶ cm³
1 kg⁻¹ = 10⁻³ g⁻¹
Multiply factors:
= 10⁶ × 10⁻³ = 10³
= 6.67 × 10⁻¹¹ × 10³
= 6.67 × 10⁻⁸ cm³ s⁻² g⁻¹
So, N m² kg⁻² = m³ s⁻² kg⁻¹
Convert units:
1 m³ = 10⁶ cm³
1 kg⁻¹ = 10⁻³ g⁻¹
Multiply factors:
= 10⁶ × 10⁻³ = 10³
= 6.67 × 10⁻¹¹ × 10³
= 6.67 × 10⁻⁸ cm³ s⁻² g⁻¹
Short Notes: Conversion of Units
1. Concept
Unit conversion is the process of expressing a physical quantity in different units without changing its value.2. Basic Conversions
- 1 kg = 10³ g- 1 m = 10² cm
- 1 km = 10³ m
- 1 h = 3600 s
- 1 ly = 9.46 × 10¹⁵ m
3. Derived Units
- Force: 1 N = 1 kg m s⁻²- Energy: 1 J = 1 kg m² s⁻²
- Gravitational constant: G = N m² kg⁻² = m³ s⁻² kg⁻¹
4. Method
1. Write given quantity2. Replace units with conversions
3. Apply powers correctly
4. Multiply and simplify
5. Important Tips
- Always use powers of 10- Treat units like algebra
- Check final unit carefully
📘 Unit Conversion Master Structure (NEET + CBSE)
📊 1. Basic Conversion Table
| Quantity | SI Unit | Conversion |
|---|---|---|
| Mass | kg | 1 kg = 10³ g |
| Length | m | 1 m = 10² cm |
| Length | km | 1 km = 10³ m |
| Time | hour | 1 h = 3600 s |
| Force | Newton | 1 N = 1 kg m s⁻² |
| Energy | Joule | 1 J = 1 kg m² s⁻² |
| Gravitational Constant | G | N m² kg⁻² |
🌟 2. Power Conversion Rules
| Base Unit | Conversion Power |
|---|---|
| m → cm | 10² |
| m² → cm² | 10⁴ |
| m³ → cm³ | 10⁶ |
| kg → g | 10³ |
| s → h | 3600 |
| s⁻² → h⁻² | (3600)² |
🧠 3. Mnemonic Trick
Mnemonic: “M K G H L J N G”
Meaning:
M → Meter
K → Kilometer
G → Gram
H → Hour
L → Light Year
J → Joule
N → Newton
G → Gravitational Constant
Memory Line:
“My King Gives High Level Job New Goals”
Meaning:
M → Meter
K → Kilometer
G → Gram
H → Hour
L → Light Year
J → Joule
N → Newton
G → Gravitational Constant
Memory Line:
“My King Gives High Level Job New Goals”
⚡ 4. Fast Solving Method
STEP 1 → Convert each unit separately
STEP 2 → Apply power rules carefully
STEP 3 → Multiply all factors of 10
STEP 4 → Write final answer in scientific notation
Shortcut:
“One unit at a time + power rule = fast solution”
STEP 2 → Apply power rules carefully
STEP 3 → Multiply all factors of 10
STEP 4 → Write final answer in scientific notation
Shortcut:
“One unit at a time + power rule = fast solution”
🧪 NEET Practice Questions - Unit Conversion & Dimensions
🟢 1. Direct MCQs (Single Correct Option)
Q1. 1 kg m² s⁻² is equal to:
A) 10⁵ g cm² s⁻²
B) 10⁷ g cm² s⁻²
C) 10⁶ g cm² s⁻²
D) 10⁸ g cm² s⁻²
A) 10⁵ g cm² s⁻²
B) 10⁷ g cm² s⁻²
C) 10⁶ g cm² s⁻²
D) 10⁸ g cm² s⁻²
Answer: B
Q2. 1 m is equal to:
A) 10⁻¹⁵ ly
B) 10⁻¹⁶ ly
C) 10⁻¹⁴ ly
D) 10⁻¹³ ly
A) 10⁻¹⁵ ly
B) 10⁻¹⁶ ly
C) 10⁻¹⁴ ly
D) 10⁻¹³ ly
Answer: B
Q3. 3 m s⁻² equals:
A) 3.9 × 10³ km h⁻²
B) 3.9 × 10⁴ km h⁻²
C) 3.9 × 10⁵ km h⁻²
D) 3.9 × 10² km h⁻²
A) 3.9 × 10³ km h⁻²
B) 3.9 × 10⁴ km h⁻²
C) 3.9 × 10⁵ km h⁻²
D) 3.9 × 10² km h⁻²
Answer: B
Q4. SI unit of G is:
A) N m² kg⁻²
B) kg m³ s⁻²
C) m² s⁻² kg
D) N m kg⁻²
A) N m² kg⁻²
B) kg m³ s⁻²
C) m² s⁻² kg
D) N m kg⁻²
Answer: A
🟡 2. Statement-Based Questions
Q5. Statement I: 1 m³ = 10⁶ cm³
Statement II: Volume depends on cube of length
A) Both true, II explains I
B) Both true, II not explanation
C) I true, II false
D) I false, II true
Statement II: Volume depends on cube of length
A) Both true, II explains I
B) Both true, II not explanation
C) I true, II false
D) I false, II true
Answer: A
Q6. Statement I: 1 N = 1 kg m s⁻²
Statement II: Newton is derived unit
A) Both true, II explains I
B) Both true, II not explanation
C) I false, II true
D) I true, II false
Statement II: Newton is derived unit
A) Both true, II explains I
B) Both true, II not explanation
C) I false, II true
D) I true, II false
Answer: A
🔴 3. Assertion & Reason
Q7.
A: 1 m² = 10⁴ cm²
R: Area depends on square of length
A) Both true, R explains A
B) Both true, R not explanation
C) A true, R false
D) A false, R true
A: 1 m² = 10⁴ cm²
R: Area depends on square of length
A) Both true, R explains A
B) Both true, R not explanation
C) A true, R false
D) A false, R true
Answer: A
Q8.
A: G has dimensions L³ M⁻¹ T⁻²
R: G = N m² kg⁻²
A) Both true, R explains A
B) Both true, R not explanation
C) A false, R true
D) A true, R false
A: G has dimensions L³ M⁻¹ T⁻²
R: G = N m² kg⁻²
A) Both true, R explains A
B) Both true, R not explanation
C) A false, R true
D) A true, R false
Answer: A
🔵 4. Match the Columns
| Column A | Column B |
|---|---|
| 1 N | kg m s⁻² |
| 1 m² | 10⁴ cm² |
| 1 J | kg m² s⁻² |
| 1 kg | 10³ g |
Answer: A-2, B-1, C-3, D-4
🔥 5. Hard Questions
Q12. Convert 5 m s⁻² into km h⁻²
A) 5.4 × 10⁴
B) 6.2 × 10⁴
C) 4.8 × 10⁴
D) 3.6 × 10⁴
A) 5.4 × 10⁴
B) 6.2 × 10⁴
C) 4.8 × 10⁴
D) 3.6 × 10⁴
Answer: A
Q13. 1 m in light year:
A) 10⁻¹⁵ ly
B) 10⁻¹⁶ ly
C) 10⁻¹⁴ ly
D) 10⁻¹³ ly
A) 10⁻¹⁵ ly
B) 10⁻¹⁶ ly
C) 10⁻¹⁴ ly
D) 10⁻¹³ ly
Answer: B
🧠 Exam Tips
✔ Convert stepwise
✔ Square and cube units carefully
✔ Use scientific notation
✔ Check final dimensions
✔ Avoid skipping steps
✔ Square and cube units carefully
✔ Use scientific notation
✔ Check final dimensions
✔ Avoid skipping steps
🧩 5. Concept Flow
Physical Quantity → Base Units (kg, m, s) → Derived Units (N, J, G) → Conversion Factors (10ⁿ) → Final Answer
🔥 6. Exam Strategy
✔ Convert step by step
✔ Always check power of units
✔ Use scientific notation
✔ Verify final dimensions
✔ Avoid skipping steps in NEET
✔ Always check power of units
✔ Use scientific notation
✔ Verify final dimensions
✔ Avoid skipping steps in NEET
🏆 Final Formula
Convert separately → Apply power → Multiply → Verify unit
