# Force Tension

Hi! Another Physics homework question that needs solving immediately! Thank you in advance.

A computer base unit of mass 7.5 kg is dragged along a smooth desk. If the normal contact force is 23 N and the tension in the arm of the person dragging it acts at 23° to the horizontal, then what is the total tension in the persons arm?

## Answers and Replies

Andrew Mason
Science Advisor
Homework Helper
It seems to me that you have left out a material fact. You will need to tell us what the co-efficient of kinetic friction is.

AM

It seems to me that you have left out a material fact. You will need to tell us what the co-efficient of kinetic friction is.

AM
There can't be a coefficient of kinetic friction if there is no friction right, and there is no friction because it is smooth desk, right?

Andrew Mason
Science Advisor
Homework Helper
Being smooth does not necessarily imply a 0 coefficient of friction. Roads can be smooth too, but they have friction. But in looking at it again, it appears here that the question expects you to assume that it is negligible.

What does the fact that the normal force is 23N tell you?

AM

Last edited:
Being smooth does not necessarily imply a 0 coefficient of friction. Roads can be smooth too, but they have friction. But it appears here that the question expects you to assume that it is negligible.

What does the fact that the normal force is 23N tell you?

AM
I think I got it. Would it make sense to solve it this way?
∑ Forces in y direction = Force Normal - Force gravity + Force tension in y direction

Andrew Mason
Science Advisor
Homework Helper
I think I got it. Would it make sense to solve it this way?
∑ Forces in y direction = Force Normal - Force gravity + Force tension in y direction
Yes. That would be right.

AM