motion sensor rider ramp direction of motion Fig. 1 Fig. 1 shows a skateboard rolling towards a ramp in a sports hall. A motion sensor records the skateboar...
Question 1 Report
Fig. 1 shows a skateboard rolling towards a ramp in a sports hall. A motion sensor records the skateboard's speed just before it reaches the ramp. The board and rider have a combined mass of 55 kg and move at 3.0 m/s. The rider then rolls up the ramp and comes briefly to rest at a higher point. The coach discusses how motion changes when gravitational potential energy increases.
(a) Give the momentum of the rider and skateboard just before the ramp. [2]
(b) Describe what happens to the skateboard's velocity as it travels up the ramp. [2]
(c) Explain why the skateboard eventually stops on the ramp. [1]
Answer Details
(a) \[p=mv=55\times3.0=165\ \text{kg m/s}.\] [2]
(b) The skateboard's speed decreases as it travels up the ramp. Its direction also changes as it follows the ramp, so its velocity decreases. [2]
(c) Energy is transferred to gravitational potential energy as the skateboard rises, and resistive forces also act. It therefore decelerates until it comes to rest. [1]
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