mechanic

☆小力士★

Bungy jumping os an exciting sport that started in New Zealand. The person has a strong piece of elastic tied to his ankles.He then jumps from a bridge.

Length of the elastic when not stretched=50m

Height of the bridge over water=80m

Mass of the boy=50kg

(a) Find the velocity of the boy when the elastic is just taut.

(b) When the elastic extends,the elastic stores elastic potential energy.When the elastic fully stretched,the loss in potential energy of the bungy jumper is equal to elastic potential energy.At full extension,the elastic potential energy is 38920J. Find the maximum extension of the elastic .Does the boy go into the water?

(c)Different people try bungy jumping.What adjustment should be made to the apparatus?

imsd

a)
s=20,a=10,u=0
v^2-u^2=2as
v=31.6ms-1

b)
38920=mgh=50x10xh
h=77.84m

so冇事

c)

length of the elastic


唔知有冇錯呀~