# Statics Problem Tipping Refrigerator

1. Apr 28, 2015

### spacetimedude

1. The problem statement, all variables and given/known data
A refrigerator with a mass of 100kg measures 150cm high by 75 cm wide by 75 cm deep. How much force applied horizontally at the top edge of the front will make it start tipping backward? Assume that the center of mass is at the center of the refrigerator.

2. Relevant equations
Moment= r x F

3. The attempt at a solution
I do not know how to start this problem. I have drawn a 3D figure of the refrigerator and have ∑Fy=mg+N (vector) and ∑Fx=F+Ff (force applied+force of friction, again vector). All the previous examples I was given were the typical ladder leaning on the wall type of questions but this one has three dimensions.

Any tips will be appreciated.

2. Apr 28, 2015

### PhanthomJay

You can look at this in 2D. A rectangle 150 cm tall and 75 cm wide with a force applied horizontally at the top. Note that for tipping to occur, the normal force must all be located where?

3. Apr 28, 2015

### spacetimedude

Is the normal force located at the bottom edge of the rectangle since when it is tipping, it is focused on one place?

4. Apr 28, 2015

### PhanthomJay

Focused in one place yes but where along the bottom edge?

5. Apr 28, 2015

### spacetimedude

I was just thinking as a rectangle so on the vertex, but do we have to consider the depth in 3D as well?

6. Apr 28, 2015

### haruspex

To be pedantic, it says the force is applied at the front top edge. Your FBD should be a side view, so the depth matters but the width doesn't. However, since depth and width are equal here it's the same either way.

7. Apr 28, 2015

### SammyS

Staff Emeritus
Gosh! I wanted to see the 3D figure, but then it occurred to me,"I only have a 2D monitor."