a) Find the speed at which Superman (mass=76.0 kg) must fly into a train (mass =

Question

a) Find the speed at which Superman (mass=76.0 kg) must fly into a train (mass = 18781 kg) traveling at 70.0 km/hr to stop it.

b) Running into the train at that speed would severely damage both train and passengers. Calculate the minimum time Superman must take to stop the train, if the passengers experience an average horizontal force of 0.440 their own weight.

c) How far does the train then travel while being slowed to a stop?

a) Find the speed at which Superman (mass=76.0 kg) must fly into a train (mass = 18781 kg) traveling at 70.0 km/hr to stop it. b) Running into the train at that speed would severely damage both train and passengers. Calculate the minimum time Superman must take to stop the train, if the passengers experience an average horizontal force of 0.440 their own weight. c) How far does the train then travel while being slowed to a stop?

Explanation / Answer

conservation of momentum

87*v - 19348*70 = 0

v=15567 km/hr = 4324 m/s

b) v = v0 + a t

0 = 19.44 - 9.81*0.5 *t

t=3.96 s

c) v^2 = v0^2 + 2 a x

0 = 19.44^2 - 2*0.5*9.81*x

x=38.5 m

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