A skateboarder of mass is coasting in a straight line along a horizontal
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A skateboarder of mass 70kg is coasting in a straight line along a horizontal, frictionless track at a constant velocity of 2.0m/s. The skateboarder suddenly throws a 5.0kg backpack straight backward at 6.0m/s relative to the ground. Neglect air resistance.
(a) Determine the velocity of the skateboarder immediately after releasing the backpack. Include magnitude and direction relative to the ground.
(b) Calculate the magnitude of the impulse experienced by the backpack during the throw and the magnitude of the impulse experienced by the skateboarder–skateboard combination. Compare these values and explain any similarities or differences.
(c) Describe the motion of the center of mass of the skateboarder–backpack system before, during, and after the throw. Provide reasoning that refers to external forces.