# Acceleration and roller coaster question that I cannot figure out

• kevin2365
In summary: From the work done on the car by the driver in moving it.So at t2 the car has kinetic energy equal to the work done on it by the driver.

#### kevin2365

Homework Statement
i need some help with these two questions I cannot figure out the equations especially for the second one if anyone could help that would be great, thanks

1. A 65.0 kg rock is moved 12.0 m across a frozen
lake. If it is accelerated at a constant rate of 0.561 m/s^2 and the force of friction is ignored, calculate the work done.

2A roller coaster at a popular amusement park has a portion of the track that is similar to the diagram provided. Assuming that the roller coaster is frictionless, find its speed at the top of the loop.
the picture is posted for this one as well as well.
Relevant Equations
some of the equations i have tried to use but don't quite work are EP=mpg as as well as w=fxd

This forum doesn't work like this: you post the problem, some guy/gal posts the solution.
You have to give your thought on how to solve them, what equations you can find useful.
So do this, or this post will get locked (or maybe even deleted) by moderators.

the issue is that I'm really confused with these two questions and I'm not sure how to solve them that's why I'm looking for some help.

kevin2365 said:
the issue is that I'm really confused with these two questions and I'm not sure how to solve them that's why I'm looking for some help.

Per the PF rules, you need to at least post the equations you think are relevant and your attempt at a solution.

dextercioby said:
This forum doesn't work like this: you post the problem, some guy/gal posts the solution.
You have to give your thought on how to solve them, what equations you can find useful.
So do this, or this post will get locked (or maybe even deleted) by moderators.
i have added some of the equations that I have attempted to use but they don't work because none of them have anything to do with acceleration

kevin2365 said:
i have added some of the equations that I have attempted to use

Please use the PF LaTeX feature for equations. You can find a "LaTeX Guide" link at the bottom left of the edit window for posts.

kevin2365 said:
Relevant Equations:: some of the equations i have tried to use but don't quite work are EP=mpg as as well as w=fxd

I don't know what EP=mpg means. I assume w=fxd means work equals force times distance; generally there is no need to explicitly include a symbol for multiplication.

Why do you think work = force times distance doesn't quite work? What have you tried to do with it?

nevermind for the first question i figured it out

kevin2365 said:
nevermind for the first question i figured it out

Ok, what about relevant equations and an attempt at a solution for the second part?

Notice at t1 the car is at rest ie it has v0=0 and it has potential energy.

what happens at t2? it is lower and now has some kinetic energy.

where did the kinetic energy come from?