Consider two cars A and B. Car A is raised to some height h inside a...

Consider two cars A and B. Car A is raised to some height h inside a service station, and car B is speeding down the highway. Describe the potential, kinetic, and total energies of each car. How much work is used to raise A to height h? What happens to the kinetic energy of B if its speed is doubled?

Would car A gravitational potential energy because work is done in elevating it?

Please help! Physics is like a complete foreign language to me and I've been trying to figure this question out for days to no avail! Any assistance you can offer would be greatly appreciated!

Homework Answers

Answer #1

For car A:

Its Potential energy(P.E) is equal to = m*g*h <----- assuming the ground level as the Zero Potential level

g = 9.8 m/s2

Its Kinetic energy(K.E) is 0 <---- assuming it is static at that point

So, total energy = mgh + 0 = mgh

Now, for B :

P.E = m*g*h'

where h' = height above which the car is located from the ground

K.E = 0.5*mv^2

where v = speed of the car B at that instant

So, total energy = mgh' + 0.5*mv^2

Now, work done to raise A to height h = -m*g*h <------ NOTE the -ve sign due to gravity acting downwards

Kinetic energy is proportional to v^2 . So if speed is doubled, the Kinetic energy will quadruple (4 times)..

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