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Acceleration from Distance and Time
The student held the trolley stationary and then released it. The trolley moved along the runway with a constant acceleration. The student recorded the time taken for the trolley to travel a measured distance along the runway.
Describe how the acceleration of the trolley can be calculated using the time taken and distance travelled by the trolley.
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Marking points
- 1 Calculates mean velocity as distance divided by time, or uses an accepted constant-acceleration equation.
- 2 Uses the fact that, from rest with constant acceleration, final velocity is twice mean velocity.
- 3 Calculates acceleration as change in velocity divided by time, or completes a correct accepted alternative route.
Full-mark answer
Calculate the mean velocity by dividing the measured distance by the time. Because the trolley starts from rest and accelerates constantly, its final velocity is twice the mean velocity. Then divide the change in velocity (the final velocity) by the time to obtain the acceleration.
Why this answer loses marks
Acceleration is distance divided by time.
Distance divided by time gives mean velocity; the method must then find final velocity and divide its change by time, or use an accepted constant-acceleration equation.