# Homework Help: Help with physics question

1. Jun 8, 2007

### kar_04

help with physics question plz

Some sliding rocks approach the base of a hill with a speed of 16 m/s. The hill rises at 40degrees above the horizontal and has coefficients of kinetic and static friction of .420 & .610 respectively, with these rocks. A) find the acceleration of the rocks as they slide up the hill. B) if it slides down, find its acceleration on the way down

F=F(static) + F (kinetic)

i'm not sure how to approach this problem. I first tried finding the vector velocities but that didn't work too well...

2. Jun 8, 2007

### Staff: Mentor

What forces act on the rocks as they slide up the hill? (Don't add static and kinetic friction--in any given situation, only one acts.)

3. Jun 8, 2007

### kar_04

as they slide up it would be the applied force??..but i'm not sure how to find that

4. Jun 8, 2007

### Staff: Mentor

I see no mention of any applied force. What other forces act on the rocks?

5. Jun 9, 2007

### esalihm

as always try to draw a free body diagram
resolve the forces into proper components