Applied force increase/decrease kinetic energy

[kerrynet32]

Homework Statement

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?

Homework Equations

K= (mv^2)/2

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?

 

[frogjg2003]

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

1. If you increase the mass and/or volume

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

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

2. If you decrease the mass and/or volume

Same as above

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

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)?

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

 

[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

 

[frogjg2003]

Yes, that's correct.