- #1

Matt Armstrong

## Homework Statement

A sturdy wooden plank, 4 meters in length and having a mass of 42 kg, is rests on 2 supports placed 1.2 meters from each end. Suppose a man of 72 kg stands 1 meter from the right end of the board. What are the upward forces on each board?

|---L----R-M--|

Where L is the left support, R is the right support, and M is the man.

## Homework Equations

ΣFy = 0

Στ = 0

τ_R = F_R * .8, τ_L = F_L * .8

Total gap between supports is 1.6 meters.

Weight of man = 705.6 N

Weight of board = 411.6 N

## The Attempt at a Solution

Each support is located .8 meters away from the board, and thus I have written out those equations above. I know that the torque produced by the man is equal to his weight, as he is 1 meter away from both the center and the edge of the board, and I am assuming the torque of the board is also equal to its weight. I also know that in problems similar to this, like cantilevers, the force of the left support will actually be downward, instead of upward.

I know that if I have the force of the right support, I can figure out the support of the left. At first, I tried to figure the force of the right support out by adding the torques of the man and board together and then solving for F_R, but in hindsight I am not confident that is the correct way to go about it.