A sled of mass m = 5 kg is resting on the snow. A girl of mass m = 50 kg is running towards the sled at v = 0.4 m/s. She jumps on the sled.
a. calculate the speed of the system after the collision. Is the collision elastic? Why can we neglect friction and use conservation of momentum?
b. when the girl and the sled are standing on the snow, she jumps off the sled, applying a force F = 100N for t = 0.002 s. What is the final velocity of the sled? Again, why can you neglect friction?