# Homework Help: Calculating Ek At a specific point

1. Nov 8, 2008

### Articulum

1. The problem statement, all variables and given/known data

I need to find out the Ek at "B" this is the diagram i got i want to know if its right and if it is why do i use the Height of 50 to find out Ek at "B"

2. Relevant equations

Ek=Ep

3. The attempt at a solution

Ek=Ep
Ek=m.g.h
Ek=100x9.8x50
Ek=49000J

2. Nov 8, 2008

### tiny-tim

Welcome to PF!

Hi Articulum! Welcome to PF!
Yes, that's right! …

(except it's really change in Ek = change in Ep) …

but why were you worried about using 50 for B?

3. Nov 8, 2008

### Articulum

Re: Welcome to PF!

If i'm figuring out Ek at "B" shouldn't i use the height also at "B"?

4. Nov 9, 2008

### borgwal

The *change* in kinetic energy plus the *change* in potential energy equals zero here: so you do need to use the height at B, or more precisely, what matters is the *difference* in height between A and B.

Probably the picture is badly drawn, I suppose the difference in height between A and B is 50m [the units for height are missing, too].

5. Nov 9, 2008

### Articulum

So i use the Diffrence in height of where it starts and where the point is?

6. Nov 9, 2008

Exactly!

7. Nov 9, 2008

### Articulum

Thank you so much made my Physics work much easier