# Determining the weight of an object, given force to move it

## Homework Statement

This is the second part of a problem. In the first problem I determined friction coefficient of an 8N block requiring 2.9 N of force to move is .3625.

The second part of this problem asks: If a weight is added to the block and it now requires 5.7 N to move both at a constant acceleration, what would the weight of the block be?

w=mg
f=uN
u=f/N

## The Attempt at a Solution

I attempted to use the friction coefficient I found in the first problem and set it up as N=f/u. This provided me with the wrong answer.

## Answers and Replies

Doc Al
Mentor
I attempted to use the friction coefficient I found in the first problem and set it up as N=f/u. This provided me with the wrong answer.
That method should work just fine, assuming you understand how N relates to the answer they want. Are they asking you to provide the amount of weight added to the block?

That method should work just fine, assuming you understand how N relates to the answer they want. Are they asking you to provide the amount of weight added to the block?

The way the question is set up I believe they want the total weight

Doc Al
Mentor
The way the question is set up I believe they want the total weight
To get the total weight of the block plus whatever was added, the method you showed would be correct.

The wording of the question seemed a bit ambiguous to me--they could also have been asking for the weight added to the block.