Question

[SHOW YOUR WORK] A 2000 kg car at rest at the top of a 1000 meter
high hill rolls down to the bottom. a) Assuming no friction is acting to slow
down the car as it rolls down the hill, how fast is it going when it reaches
the bottom of the hill? b) Assuming that there is friction stopping the car
when it reaches the bottom of the hill - how much work is done to stop
the car? c) How much friction force is required to stop the car in 100
meters?

Answer 1

Answer:

Explanation:

Potential energy is converted to kinetic energy

½mv² = mgh

a) v = √2gh = √2(9.8)(1000) = 140 m/s

Assuming the car is now on horizontal ground, The work will convert the kinetic energy to friction heat

b) W = ½mv² = ½(2000)140² =  19,600,000 J = 19.6 MJ

c) W = Fd

   F = 19600000/100 = 196000 N = 196 KN

Sounds like a job for a parachute!!!

Answer 2

Answer:

a) 140 m/s

b)  19.6 MJ

c) 196 KN

Explanation: