# Homework Help: Finding normal force

Tags:
1. Aug 27, 2015

### Pizza Dave

A 41 kg crate rests on a horizontal floor and a 67kg person is standing on the crate.

a. determine the magnitude of the normal force the floor exerts on the crate

b. determine the magnitude of the normal force that the crate exerts on the person

2. Relevant equations

(m1+m2)G
M2(G)

3. The attempt at a solution

a. 1080
b. 670

2. Aug 27, 2015

### AlephNumbers

Try drawing a force diagram for both the person on the crate and the crate and try summing your forces for each individually. The answers should become clear!

Also, this belongs in introductory physics.

3. Sep 1, 2015

### carl_loves_math

AlephNumbers, this was an impertinent response.

Pizza Dave, you calculated this answer correctly, but it looks like you substituted 10 for the force of gravity instead of the actual value of 9.8. This may help your answers be more accurate in the future!

4. Sep 2, 2015

### haruspex

You should always specify units (unless instructed otherwise).
Both values are just approximations. Often students are told to use 10 ms-2. On the other hand, if it is approximated to 10 then, logically, the answers should only be given to the same precision, e.g. 1100 N for (a).
And you mean gravitational acceleration, not force.