Class 11 Physics – 100 Important Questions &
Answers Exam Format with Rationales
GUARANTEED PASS | ALREADY GRADED A+
Section A: Units & Measurements (Questions 1–10)
Q1: The dimensional formula of force is:
A: MLT⁻²
Rationale: Force = mass × acceleration. Mass (M), acceleration = LT⁻² → MLT⁻².
Q2: The number of significant figures in 0.00250 is:
A: 3
Rationale: Leading zeros are not significant. Trailing zeros after decimal are significant. (2,5,0)
Q3: Which of the following is a dimensionless quantity?
A: Strain
Rationale: Strain = change in length/original length → same dimensions cancel out.
Q4: 1 Ångstrom (Å) = ______ meters.
A: 10⁻¹⁰ m
Rationale: 1 Å = 10⁻¹⁰ m. Used for atomic distances.
Q5: The dimensional formula of angular velocity (ω) is:
A: T⁻¹
Rationale: ω = θ/t. Angle (θ) is dimensionless. Only time (T) in denominator.
Q6: If the error in measuring radius of a sphere is 2%, the error in its volume is:
A: 6%
Rationale: Volume ∝ r³. Percentage error in volume = 3 × percentage error in radius = 3×2% =
6%.
Q7: 1 light year = ______ meters.
A: 9.46 × 10¹⁵ m
Rationale: Distance light travels in one year at 3×10⁸ m/s.
Q8: The SI unit of luminous intensity is:
A: Candela (cd)
Rationale: One of the 7 base SI units. Others: kg, m, s, A, K, mol.
, Q9: Which pair has the same dimensional formula?
A: Work and Torque
Rationale: Both have ML²T⁻². Work = force×displacement; Torque = force×perpendicular
distance.
Q10: The percentage error in g = 4π²L/T² if L=1.0±0.1 m and T=2.0±0.02 s is approximately:
A: 12%
Rationale: Δg/g = ΔL/L + 2(ΔT/T) = 0.1/1.0 + 2×(0.02/2.0) = 0.1 + 0.02 = 0.12 → 12%.
Section B: Kinematics (Questions 11–20)
Q11: A car accelerates uniformly from rest to 20 m/s in 5 seconds. The acceleration is:
A: 4 m/s²
Rationale: a = (v - u)/t = (20 - 0)/5 = 4 m/s².
Q12: The slope of velocity-time graph gives:
A: Acceleration
Rationale: Slope = Δv/Δt = acceleration. Area under v-t graph = displacement.
Q13: A ball is thrown vertically upward with velocity 20 m/s. Maximum height reached is (g=10
m/s²):
A: 20 m
Rationale: H = u²/(2g) = (20)²/(2×10) = 400/20 = 20 m.
Q14: The area under acceleration-time graph gives:
A: Change in velocity
Rationale: ∫a dt = Δv.
Q15: A body moving with constant speed in a circle has:
A: Centripetal acceleration
Rationale: Direction changes continuously, so velocity changes, hence acceleration exists
toward center.
Q16: The equations of motion (v = u + at, etc.) are valid for:
A: Uniform acceleration
Rationale: Derived assuming constant acceleration. Not valid for variable acceleration.
Q17: A stone is dropped from a height of 80 m. Time to reach ground (g=10 m/s²):
A: 4 seconds
Rationale: s = ut + ½at² → 80 = 0 + ½×10×t² → t² = 16 → t = 4 s.
Answers Exam Format with Rationales
GUARANTEED PASS | ALREADY GRADED A+
Section A: Units & Measurements (Questions 1–10)
Q1: The dimensional formula of force is:
A: MLT⁻²
Rationale: Force = mass × acceleration. Mass (M), acceleration = LT⁻² → MLT⁻².
Q2: The number of significant figures in 0.00250 is:
A: 3
Rationale: Leading zeros are not significant. Trailing zeros after decimal are significant. (2,5,0)
Q3: Which of the following is a dimensionless quantity?
A: Strain
Rationale: Strain = change in length/original length → same dimensions cancel out.
Q4: 1 Ångstrom (Å) = ______ meters.
A: 10⁻¹⁰ m
Rationale: 1 Å = 10⁻¹⁰ m. Used for atomic distances.
Q5: The dimensional formula of angular velocity (ω) is:
A: T⁻¹
Rationale: ω = θ/t. Angle (θ) is dimensionless. Only time (T) in denominator.
Q6: If the error in measuring radius of a sphere is 2%, the error in its volume is:
A: 6%
Rationale: Volume ∝ r³. Percentage error in volume = 3 × percentage error in radius = 3×2% =
6%.
Q7: 1 light year = ______ meters.
A: 9.46 × 10¹⁵ m
Rationale: Distance light travels in one year at 3×10⁸ m/s.
Q8: The SI unit of luminous intensity is:
A: Candela (cd)
Rationale: One of the 7 base SI units. Others: kg, m, s, A, K, mol.
, Q9: Which pair has the same dimensional formula?
A: Work and Torque
Rationale: Both have ML²T⁻². Work = force×displacement; Torque = force×perpendicular
distance.
Q10: The percentage error in g = 4π²L/T² if L=1.0±0.1 m and T=2.0±0.02 s is approximately:
A: 12%
Rationale: Δg/g = ΔL/L + 2(ΔT/T) = 0.1/1.0 + 2×(0.02/2.0) = 0.1 + 0.02 = 0.12 → 12%.
Section B: Kinematics (Questions 11–20)
Q11: A car accelerates uniformly from rest to 20 m/s in 5 seconds. The acceleration is:
A: 4 m/s²
Rationale: a = (v - u)/t = (20 - 0)/5 = 4 m/s².
Q12: The slope of velocity-time graph gives:
A: Acceleration
Rationale: Slope = Δv/Δt = acceleration. Area under v-t graph = displacement.
Q13: A ball is thrown vertically upward with velocity 20 m/s. Maximum height reached is (g=10
m/s²):
A: 20 m
Rationale: H = u²/(2g) = (20)²/(2×10) = 400/20 = 20 m.
Q14: The area under acceleration-time graph gives:
A: Change in velocity
Rationale: ∫a dt = Δv.
Q15: A body moving with constant speed in a circle has:
A: Centripetal acceleration
Rationale: Direction changes continuously, so velocity changes, hence acceleration exists
toward center.
Q16: The equations of motion (v = u + at, etc.) are valid for:
A: Uniform acceleration
Rationale: Derived assuming constant acceleration. Not valid for variable acceleration.
Q17: A stone is dropped from a height of 80 m. Time to reach ground (g=10 m/s²):
A: 4 seconds
Rationale: s = ut + ½at² → 80 = 0 + ½×10×t² → t² = 16 → t = 4 s.
