Question

The angle between a 180-pound force F and AB= 5i + 2j is 30.Find the work done by F in moving and object from A to B.

Answer 1

the answer is option 1, A

Explanation:

Answer 2

`W=839.464\ ft*lbf`

Explanation:

The work done is the product of the magnitude of the force applied to the object by the magnitude of the displacement of the object by the cosine of the angle between the force and direction of the displacement. This is:

`W=|F|*|r|cos(\theta)`

In this case

`\theta=30\°`

|F|=180 pound force

The magnitude of vector AB is:

`|r|= √(5^2 + 2^2)\\\\|r|= √(29)\ fr`

Finally the work is:

`W=180*√(29)*cos(30\°)`

`W=839.464\ ft*lbf`