# Change in thermal energy

1. Mar 30, 2015

### Westin

1. The problem statement, all variables and given/known data

A block of mass M is pulled at constant speed with force F a distance d across a surface. Using the energy principle, what can you say about the change in thermal energy of the block?

2. Relevant equations

3. The attempt at a solution

I believe the change in thermal energy is 0 (b) because it is being pulled at a constant speed so nothing is actually changing. Is my logic correct to say it is b?

I only have one attempt left

Last edited by a moderator: May 7, 2017
2. Mar 30, 2015

### Staff: Mentor

Of it's traveling at constant speed, then what can you say about the presence or absence of a friction force?

3. Mar 30, 2015

### Westin

If you are at constant speed, that means that the acceleration you are providing is equal to the deceleration from the friction. If those are not equal then the speed is increasing or decreasing. KE isn t changing. However, heat it formed so there would be a positive change of thermal energy? So C?

4. Mar 30, 2015

Correct.