# Homework Help: Applied force increase/decrease kinetic energy

1. Feb 20, 2012

### kerrynet32

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

1. Under what conditions would an applied force increase the kinetic energy of an object?

2. Under what conditions would an applied force decrease the kinetic energy of an object?

3. What would the Force vs Distance graph look like for a cart on a track connected to a pulley and weight hanger?

2. Relevant equations

K= (mv^2)/2

3. The attempt at a solution

1. If you increase the mass and/or volume

2. If you decrease the mass and/or volume

3. Would the graph start high on the y-axis (Force) and then have a logarithmic curve decreasing on the y-axis and increasing on the x-axis (Distance)?

Are these answers correct or am I missing something?

2. Feb 20, 2012

### frogjg2003

v stands for velocity, not volume. Also, forces don't usually affect mass.

Same as above

Think about the force of gravity on a hanging weight. Does that change based on height?

3. Feb 21, 2012

### kerrynet32

Would these answers be correct then?

1. An applied for in the direction of motion to increase the object's speed would increase the kinetic energy.

2. An applied for in the opposite direction of motion to decrease the object's speed would decrease the kinetic energy.

3. The graph would be a horizontal line constant

4. Feb 21, 2012

### frogjg2003

Yes, that's correct.