# Normal force

1. Aug 30, 2006

### ljK

Hi. I have a question. When is the normal force on a wood block equal to zero?

2. Aug 31, 2006

### KyoPhan

Have you learned to calculate force normal yet? We can calculate the force normal by knowing the weight(mass and gravity) and the angle of the ramp(assuming it is a ramp). Force normal is the force applied perpendicular to the surface. So there must be a force applied to cancel out the force produced by gravity.

Imagin a heavy block on a ground. If you attempt to lift it,(without actually picking it off the ground), the force normal is decreasing due to the decreasing force that is pushing the ground.

I hope that helps.

3. Aug 31, 2006

### HallsofIvy

when there is no force pressing on the wood!

4. Aug 31, 2006

### gunblaze

Yes. Like wat HallsofIvy has said. The conditions no normal forces acting on the wood is actually when there is no force pressing on the wood.

The best place for such a thing to occur is when the block is in space where weight is negligible or zero. When this happens, there is no resultant force on the object and this results in no normal force on the object.

Normally, It occurs when one object comes into contact with another. One of the object must have a resultant force on it and when it touches the other object, the other object will act a normal force on the object to bring it to equilbrium or to cancel away the resultant.

5. Sep 1, 2006

free falling

6. Sep 1, 2006

### civil_dude

When the ramp is vertical

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