How Does Work Done on a Car Relate to Its Kinetic Energy and Speed?

[HopelessMe]

1. A car of mass 800kg is at rest. The engine exerts a resultant force of 2000 N for a distance of 5m. a) What is then its kinetic energy? b) What is then its speed?



2. It is required that you must not use any SUVAT equations while solving this problem.

Possible equations to use are:
kinetic energy = 1/2 x m x v^2
Gravitational Potential Energy = m x g x h
Work = force x distance
F = m x a
W = m x g



3. I have attempted this question a number of times as I'm trying to find the velocity, but since there is no height in this question, I can't use the GPE equation, I'm just a little bit confused and would really appreciate some help.

 

[tiny-tim]

Hi HopelessMe! Welcome to PF!

Try work = force x distance. ​

(btw, strictly, it's force "dot" displacement)

 

[HopelessMe]

Force x distance = 2000 N x 5 m = 10000 J

Okay, how do I use 10 000 J :shy:

 

[tiny-tim]

Do you know the work energy theorem?

 

[HopelessMe]

Do you know the work energy theorem?

Hey Tiny-Tim,

I don't believe I'm aware of the theorem. I know that work is the energy that's been changed from one form to another...

 

[HopelessMe]

So do you mean to say that the work done is equal to the kinetic energy?

 

[tiny-tim]

So do you mean to say that the work done is equal to the kinetic energy?

work done equals the increase in mechanical energy …

that's kinetic energy plus various forms of potential energy​

(haven't your lectures covered this?

if not, look it up)