# Homework Help: Machines Problem

1. Dec 9, 2007

### aquamarine08

[SOLVED] Machines Problem

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

A ramp, 18m long and 4.5m high is set up in order to wheel a 25-kg box at a constant speed. Assume that by wheeling it there is no friction.

2. Relevant equations

IMA= $$\frac{d_{in}}{d_{out}}$$

3. The attempt at a solution

I know this is a pretty simple problem but I don't know how to tell which distance is "in"and which is "out".

Please help, I can't find any sample problems in my book and we never got any practice in class...and I have a test tomorrow! :( Thank you.

2. Dec 9, 2007

### mgb_phys

What are you trying to find out - what is the actual question ?

3. Dec 9, 2007

### aquamarine08

o, im sorry, I have to find the IMA and MA... (ideal mechanical advantage and mechanical advantage).

4. Dec 9, 2007

### mgb_phys

Ok, I hadn't seen the acronym before.
Mechanical advantage is generally = distance you apply the force over / distance work is done.
So in an inclined plane = length of slope / height of slope
If there is no friction then Ideal MA would = MA

To work out which way up, you would generally want a MA > 1 so you do less work for a longer distance to move a heavy load a short distance.

ps. Although not always, high gear on a bike has fractional mechanical advantage so you apply a large force over a small diustance to move the bike wheel a large distance with low force.

Last edited: Dec 9, 2007
5. Dec 9, 2007

### aquamarine08

ok thanks so much!! :D