is the height above ground in meters. A 100 kg car has 30,000 J of potential ene

Question

is the height above ground in meters. A 100 kg car has 30,000 J of

potential energy at point A. It moves down a frictionless track and comes to a stop as it compressa huge spring at point D.

(a).On the diagram below, sketch the energy bar graphs when the car is at the indicated points. (b). How much kinetic energy does the car have at point C? Explain or calculate. (c) How fast is car moving at point B? Explain or calculate. (d). How much elastic potential energy does the car have at point D? Explain or calculate.

Explanation / Answer

Given
mass of car m = 100 kg, at point A it has potential energy = 30000 J = mgh ==> g = 10 m/s2

as the track is frictionless the conservation energy takes place

total mechanical energy of the system is constnat

At A Eg = 30,000 J, Ek = 0 J, Eel = 0J

At B Eg = 10000 J, Ek = 20000 J, Eel = 0 J

At C Eg = 0 J , Ek = 30000 J , Eel = 0 J

At D Eg = 10000J,Ek = 20000 J ,Eel = 20000J
  

b) at point C the total energy is in the form of k.e only because on the groung the p.e =0 J

c) at point B the k.e = 20000 = 0.5*10000*v^2   ==> v = 2 m/s

d) the elastic potential energy = 0.5 kx^2 = 0.5 mv^2 ===> Eel = 20000 J

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