# I don't know how to write expressions for these questions. Someone please help?

An object of mass m is initially moving forward when a net force F acts on the object in the forward direction. While the force is applied, the object travels a distance x in a time t. Write expressions for the following:

(b) The amount that the object's kinetic energy increases

(c) The amount that the object's momentum increases

(d) The amount that the object's speed increases

Anonymous is wrong. Nice try though

I put in Anonymous's answer and it was wrong.

I hate Physics and I don't understand it. Why they make us take this class I don't know.

### 2 Answers

- Anonymous5 years agoFavorite Answer
Use Newton's second law F=ma

and

v^2 = u^2 + 2as

v^2=u^2 + 2Fs/m

v^2-u^2=2Fs/m

1/2m(v^2-u^2) = Fs

1/2mv^2-1/2mu^2 = Fs LHS is change in KE for ans(b)

The RHS : Fs =force x distane or work done

So, the work done is the change in kinetic energy from the work energy theorem.

Use: v = u+at

v = u +Ft/m

v-u =Ft/m

m(v-u) =Ft

mv-mu =Ft LHS = change in momentum for ans c)

Again,

Use: v = u+at

v = u +Ft/m

v-u =Ft/m LHS change in velocity and ans d)

Wrong! please explain yourself anon questioner!

- 5 years ago
Correct answer by anon given the question. I don't think that the questioner who prefers to remain anon has any idea about physics at all and one wonders what new breed of questioner Yahoo is encouraging who fails to accept the correct answer when given. I give anon answer a thumbs up. I bet the questioner could not even answer this simple question

Thumbs up. neat solution man!