All Work and No Play

Learning Goal: To be able to calculate work done by a constant force directed at different angles relative to displacement

If an object undergoes displacement while being acted upon by a force (or several forces), it is said that work is being done on the object. If the object is moving in a straight line and the displacement and the force are known, the work done by the force can be calculated as

where W is the work done by forceon the object that undergoes displacement directed at angle θ relative to .

Note that depending on the value of  cosθ , the work done can be positive, negative, or zero.

In this problem, you will practice calculating work done on an object moving in a straight line. The first series of questions is related to the accompanying figure.

A) The work done by force is

=> It is zero

B) The work done by force is

=> It is positive

C) The work done by force is

=> negative

D) The work done by force is

=> positive

E) The work done by force is

=> negative

F) The work done by force is

=> zero

G) The work done by force is

=> positive

H) Find the work W done by the 18-newton force.

=> W= 2900 J

I) Find the work W done by the 30-newton force.

=> W= 4200 J

J) Find the work W done by the 12-newton force.

=> W= -1900 J

K) Find the work W done by the 15-newton force.

W= -1800 J