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?
其實你係咪打漏d野?
elastic potential energy唔係應該=loss in pe+ loss in ke咩
wilson1993912 發表於 12-4-2009 18:41
elastic potential energy=loss in PE(mgh'=50*10*e)+ loss in KE
loss in KE(mv^2/2)=loss in PE(mgh=50*10*50)
a)v^2/2=gh
v^2=2*10*50
v=31.6 ms^-1
b)38920=mgh'
h'=38920/(50)(10)
=77.84 m
<80 m
.'.the boy won't go into the water
the maximum extension is 77.84-50=27.84 m
c)use a string with higher force constant instead
發表於 12-4-2009 15:34:38
變色卡
發表於 14-4-2009 22:34:17
