Determining speed

Question 1

Describe how you can determine the average speed of a moving trolley as it moves down a slope.

Answer 1

When you know the distance that a body moves and the time taken for the body to move that distance, you can use the equation speed = distance ÷ time to determine its speed. This can be done by measuring the distance between two points that the trolley moves past and dividing it by the time take to travel between those points, or by using light gates to measure the time for which a known length of card breaks a light beam.

Question 2

Explain how two light gates can be used to find the acceleration of a ball rolling down a slope.

Answer 2

Calculate the speed of the ball through the first light gate using speed = distance ÷ time. Calculate the speed of the ball through the second light gate. Work out the change in speed and the time difference for the two gates. Calculate the acceleration using the equation acceleration = change in speed ÷ change in time.