# Homework Help: Friction Problem

1. Apr 9, 2009

### LoveandHate

1. The problem statement, all variables and given/known data
A 2.5 kg cat is fired horizontally out of a cannon across a frozen lake. It is wearing steel tap shoes. The kinetic coefficient of friction is 0.010. If the cat's initial speed was 200 km/h, then:
a) does the cat make it all the way across the 1.0 km wide lake?
b) if so, what is its final speed on the far side of the lake?
c) if the coefficient of kinetic friction between the steel and ground on the far side of the lake is 0.50000, how far does the cat slide?

2. Relevant equations
Fg=ma
Fk=$$\mu$$kFN
FNET=ma
v22=v12+2a$$\Delta$$d

3. The attempt at a solution
a) I figured out FN by using Fg=ma and got 24.5 N [up]. I then used this to find Fk, which would equal FNET. For this value, I got 0.245 N [W]. Then I found acceleration using FNET=ma and got -0.098 m/s2. I subbed all of these numbers into the the last formula and got about 15749.56 m. I think I may have used the last formula wrong because I assumed what v2 is, but I needed to because I don't know what $$\Delta$$t is.

b) I assume that I will sub all of my calculations (the appropriate ones, of course) into the last formula and solve for v2?

c) I have no idea how to start this one.

2. Apr 9, 2009

### Thaakisfox

Your notation is a bit messy... So with the normal force and gravitational force you have a different acceleration. One is due to the friction "a" and the other is due to gravity "g". So you should write Fg=my instead... No what did you assume for v2? Think about the work-energy theorem ;)

3. Apr 9, 2009

### LoveandHate

we haven't learned that yet! and i'm confused by what you said.