Free Acceleration MCQs with Answers

1. A car accelerates uniformly from rest to 20 m s-1 in 8 s. The distance covered is

• A. 40 m
• B. 80 m
• C. 160 m
• D. 320 m

Explanation: With uniform acceleration from rest the average velocity is half the final velocity, which is 10 m s-1, and over 8 s that gives 80 m. The same answer comes from finding a as 20 divided by 8, which is 2.5 m s-2, then using S equal to half a t squared. Using the final velocity of 20 m s-1 for the whole 8 s gives the wrong answer of 160 m.

2. A stone is dropped from rest and falls freely for 3 seconds. Taking g as 10 m per second squared, the distance fallen is

• A. 15 m
• B. 30 m
• C. 45 m
• D. 90 m

Explanation: Using s equals half g t squared, the distance is half multiplied by 10 multiplied by 9, giving 45 m. The value 30 m is the velocity after 3 seconds in metres per second, offered as a distractor. Distance in free fall grows with the square of the time, not in proportion to it.

3. A car accelerates uniformly from 10 m per second to 30 m per second in 5 seconds. Its acceleration is

• A. 2 m per second squared
• B. 4 m per second squared
• C. 6 m per second squared
• D. 8 m per second squared

Explanation: Acceleration is the change in velocity divided by the time, so 20 divided by 5 gives 4 m per second squared. Dividing the final velocity by the time instead gives 6, a common slip. The distance covered in that time would be the average velocity of 20 multiplied by 5, that is 100 m.

4. A body moving with constant speed in a circle has

• A. constant velocity
• B. zero acceleration
• C. changing velocity and therefore acceleration
• D. no force acting on it

Explanation: Velocity is a vector, so a continuous change of direction is a change of velocity even at constant speed, and the acceleration points towards the centre. A net force must therefore act, supplied by tension, friction or gravity depending on the situation. Constant speed and constant velocity are not the same thing.