Measuring acceleration analysis (v=x/t, a=(v-u)/t) | Starter Quiz | Oak National Academy

A student measures the time taken for a toy parachute to fall from a particular height. She repeats the measurement and gets these results: 1.60 s, 1.53 s, 1.52 s. The mean time taken is ___ s.

A toy car travels at a constant velocity along a straight track. It travels 90 cm in 20 s. The velocity of the toy car is ___ m/s along the track.

A student measures the acceleration of a trolley along a slope for different values of the force pulling the trolley. Which of the following is the independent variable in this experiment?

• the angle of the slope

• the mass of the trolley

• the acceleration of the trolley

• the force acting on the trolley

Answer explanation

The experimenter chooses different values of the force (independent variable). They measure the acceleration (dependent variable) for each force. The mass of the trolley and angle of the slope are control variables which should be kept constant.

A trolley travels down a slope. It is stationary at the start and gets faster as it moves. A student takes measurements and calculates (distance travelled) ÷ (time taken). What has the student found?

• the speed at the start

• the speed at the end

• the average speed

• the acceleration

Answer explanation

The speed is not constant - it increases as the trolley travels. The starting speed is zero and the final speed is the top speed. The average speed is in between these two values, and is found by dividing the total distance by the total time.

A trolley is stationary at A then accelerates along the track. A student wants to measure the trolley’s average acceleration between A and C. Which of the following calculations should be used?

• (average speed between A and D) ÷ (time from A to C)

• (average speed between A and D) ÷ (time from A to D)

• (average speed between B and D) ÷ (time from A to C)

• (average speed between B and D) ÷ (time from A to D)

Answer explanation

Acceleration = change in speed ÷ time. Change in speed = (estimated speed at C) – (starting speed) = (average speed between B and D) − 0. So the best estimate of the acceleration is (average speed between B and D) ÷ (time from A to C).