Question

Is work done if you carry a book across the room at a constant velocity?
a. No, the force applied is parallel to the direction of motion.
b. Yes, the force applied is parallel to the direction of motion.
c. No, the force applied is perpendicular to the direction of motion.
d. Yes, the force applied is perpendicular to the direction of motion.

Answer 1

No.  Work is not done if you carry a book across the room
at a constant velocity?

The force applied is perpendicular to the direction of motion. (C)

Answer 2

Answer:

No, the force applied is perpendicular to the direction of motion.

Explanation:

Work done is given by :

$W=Fd\ cos\theta$

F = force

d = displacement

$\theta$ = angle between force and displacement

Work is positive when the force and the displacement are in same direction. Work is negative when the force and the displacement are in opposite direction. When the force and displacement are perpendicular to each other, no work is done.

If we carry a book across the room at a constant velocity, the work done is zero. This is because our weight is acting vertically downward and we are moving forward. The angle between the force and the displacement is 90. So, no work is done.

Hence, the correct option is (c) "No, the force applied is perpendicular to the direction of motion".