Question

The plot below shows the force exerted by a platform on Fred. He jumps. 1000 N Fred 800 N 600 N 400 N 200 N force platformm Os Is 2s 3s 4s 5s For what time or time interval is Fred motionless? At what time do Fred's feet leave the platform? What is Fred's motionless weight? What is Fred's mass? What is the net impulse delivered to Fred from 0 to 3.5 s?

Answer 1

When net force exerted by plateform remains constant , fred will be motion less and in this situation F=mg

When force starts varying , fred is trying to.jump

And when force becomes zero fred has jumped and lost contact from plateform

So

fred is motionless for 2.5 s

fred left platform at 3.5 second

freds motionless weight is 500 N

freds mass is 500/g =52.02 kg

net impuls imparted = are under force time graph during 2.5 to 3.5 second above 500 N = 150 N-s