# Rotational motion of rear wheels

1. Oct 23, 2013

### TeeNaa

A 1500 kg car is driven onto a pair of ramps so that it fronts wheels have been raised 0.3 m above the rear wheels. The wheel base of the car is 2.4m and it center of gravity is located at the midpoint between the front and rear wheels. How much of the car's weight is supported by the rear wheels? - The problem I'm having in this question is interpreting what the question is asking for. I just need on on setting up the problem as on what I should find first. Thanks

This is what I drew but I have no idea what to use to solve with these given information.

2. Oct 23, 2013

### Simon Bridge

When the car is level, it's weight is distributed evenly between the front and rear wheels, but when the front is lifted higher, more weight gets pushed onto the back than the front. Can you see why?

What has happened to the weight vector, compared with the wheel positions, to make that happen?

If you draw a free-body diagram of the situation - you get two normal forces: one from the front wheels and one from the back wheels. You also get horizontal surface forces at each wheel-set.

3. Oct 23, 2013

### TeeNaa

@Simon, thank you for the reply.
For the first question, yes I can see why the weight would be pushed back. For the second question, I don't know what that really mean. I understand why there is two normal force because of the wheel set but I do not understand the horizontal surface forces part. What would I have to find first in this case? Thanks again.

4. Oct 23, 2013

### Simon Bridge

The question involves a free body diagram where not all the forces act through the center of mass.
Other than that, it is still statics.