A air-sled glides on a cushion of air so that friction is negligible
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A 1.2kg air-sled glides on a cushion of air so that friction is negligible. A computer-controlled thruster mounted on the sled can fire in only one horizontal direction (taken to be +x). During a 6.0-s experiment, the thruster produces three distinct constant thrust levels, as summarized in the table.
Time Interval Thrust Magnitude
0 s → 2 s 4.0N
2 s → 4 s 1.5N
4 s → 6 s 0.50N
Ignore all other horizontal forces.
Complete the tasks below. Show all calculations and clearly state any reasoning.
(a) For each time interval, compute the sled’s acceleration.
(b) Sketch (on your own paper) a qualitative acceleration-versus-time graph for the 6.0-s interval. Describe in words the key features of your graph in your response.
(c) The sled is initially at rest. Determine its speed at t=6.0s.
(d) Explain how the changing thrust levels demonstrate the relationship between net external force and the rate of change of velocity.