Question

While playing a game in your backyard, you accidentally get a frisbee stuck in a tree. The frisbee has a mass of 0.130 kg. You start to poke it with a stick to try and get it down, but instead of going down it just moves to the right by a distance of 0.142 meters. While you were poking it, there were 4 forces on it:

1. Gravity

2. Normal force, upward (from a tree branch)

3. Friction force, to the left (equal to 15.7 Newtons)

4. The force from the stick - to the right and downward; equal to 38.0 Newtons, at an angle of 60.0 degrees below "to the right". What is the total work done on the ball, as it moves that distance of 0.142 meters?

______ Newton*meters

Answer 1

As the frisbee moves right means horizontally, we conclude that there is work done only by friction force and horizontal component of force exerted by stick and not by gravity and normal reaction by tree.

Now, the body moves right by 0.142 m.

friction acts on it 15.7 N towards left.

work done by friction will be negative as movement of frisbee is opposite of friction.

component of force by stick in horizontal direction towards right is 38 cos 60o = 19 N.

So, total work done = (19 x 0.142) - (15.7 x 0.142) = 0.4686 Nm.