# Force and Motion

1. Oct 20, 2009

### dortec

A 53 kg skier skis directly down a frictionless slope angled at 15° to the horizontal. Choose the positive direction of the x axis to be downhill along the slope. A wind force with component Fx acts on the skier. What is Fx if the magnitude of the skier's velocity is (a) constant, (b) increasing at a rate of 1.5 m/s2, and (c) increasing at a rate of 3.0 m/s.

2. Oct 20, 2009

### the pro

give us the atempt at the sulution then we can try to help u

3. Oct 20, 2009

### dortec

i did it and got
a: 137.17 n
b: 57.5 n
c: -22n

but im pretty sure they're wrong:P

4. Oct 20, 2009

### the pro

with wich formula

did u do this with the one of potencial energy

5. Oct 20, 2009

### dortec

sigma Fext= M.a newton's second law i think:P .. and u place the forces.. that's how i did it.

6. Oct 20, 2009

### the pro

so u did this with the second law of newton f=m x a

7. Oct 20, 2009

### dortec

yes|-) .. now can someone help me please^o)?

8. Oct 20, 2009

### Jebus_Chris

There are two forces, the force of the wind and his weight (only in the c-direction, down the ramp).

a) Constant velocity means that there is no acceleration and the net force is zero.

b/c) He is accelerating down the hill which means that there is a net force.

Draw an fbd then you can create an equation for a/b/c based on the parameters.

9. Oct 20, 2009

### the pro

u did just the forces but how about the angel thats ur failur a

10. Oct 20, 2009

### the pro

nah he did that with the f=ma parameters but u need to put the angel so if it is like u say it will go like this f=ma=53kg x o m/s2 and then he would have o N and u would do 2 and 3 like this