Question

A subway rider is unexpectedly jolted while standing and not holding a rail. The impulsive acceleration is -5.0 m/s2 lasting for 0.1 seconds. The rider is 1.7m tall, their COM is 0.95m high and their mass is 73 kg. Assume they behave like a rigid body hinged at the floor.

1. What is the shear force between the rider and floor during the impulse?

2. What is the angular velocity and energy of the rider at the end of the impulse?

3. What is the vertical force on the rider’s feet at the end of the impulse?

4. What is the minimum coefficient of friction during the impulse in order to not slip?

Answer 1