Motion — Set 1
Physics · गति · Questions 1–10 of 60
What is the SI unit of acceleration?
Correct Answer: A. m/s^2
Acceleration is the rate of change of velocity per unit time. Velocity has unit m/s, so dividing by s gives m/s^2. Therefore, m/s^2 is the SI unit.
A body starts from rest and accelerates uniformly at 2 m/s^2 for 5 s. How much distance does it cover?
Correct Answer: C. 25 m
Use s = ut + (1/2)at^2 with u = 0, a = 2, t = 5. So s = 0 + (1/2)×2×25 = 25 m. Hence, 25 m is correct.
Which statement is correct about distance and displacement?
Correct Answer: A. Distance is a scalar, displacement is a vector
Distance depends on total path length and has only magnitude, so it is scalar. Displacement depends on initial and final position with direction, so it is vector. Distance is never negative, but displacement can be negative in 1D based on direction.
In a velocity–time graph, what does the slope represent?
Correct Answer: C. Momentum
The correct answer is 'Momentum'. Slope means change in velocity divided by change in time. That quantity is acceleration by definition. So the slope of a v–t graph gives acceleration.
A person walks 3 km at 3 km/h and returns 3 km at 6 km/h. What is the average speed for the whole trip?
Correct Answer: B. 3 km/h
Average speed = total distance / total time. Time out = 3/3 = 1 h and time back = 3/6 = 0.5 h, so total time = 1.5 h. Total distance = 6 km, so average speed = 6/1.5 = 4 km/h, which is option A? Wait, check options: 4 km/h is option A, so A is correct.
In uniform circular motion, the velocity of the body is always directed along the?
Correct Answer: B. Radius away from the center
Velocity in circular motion points along the instantaneous direction of motion. That direction is tangential to the circular path. The radius direction corresponds to centripetal acceleration, not velocity.
A car moving at 20 m/s comes to rest in 4 s with uniform deceleration. What is the deceleration?
Correct Answer: A. -8 m/s^2
Use a = (v - u)/t with v = 0, u = 20, t = 4. So a = (0 - 20)/4 = -5 m/s^2. The negative sign shows retardation, so -5 m/s^2 is correct.
Which conversion is correct?
Correct Answer: D. 1 m/s = 3.6 km/h
Since 1 m = 0.001 km and 1 s = 1/3600 h, 1 m/s = 0.001×3600 km/h. That equals 3.6 km/h. Therefore, 1 m/s = 3.6 km/h is correct.
In free fall near Earth (ignoring air resistance), the acceleration of a body is approximately?
Correct Answer: C. 9.8 m/s^2 upward
The correct answer is '9.8 m/s^2 upward'. Free-fall acceleration is due to gravity and is nearly constant near Earth. Its direction is toward the center of Earth, i.e., downward. It does not depend on mass for ideal free fall.
A body has initial velocity 5 m/s and acceleration 2 m/s^2 for 3 s. What is the final velocity?
Correct Answer: A. 5 m/s
Use v = u + at with u = 5, a = 2, t = 3. So v = 5 + 2×3 = 11 m/s. Therefore, 11 m/s is the correct final velocity.