Question

A trunk is dragged 3 m across an attic floor by a force of 2 N. The work done on the trunk is ____ joules. Assuming the floor to be level, the gain in potential energy is ____ joules.

5
3
0
12
6

Answer 1

work done on trunk = force * distance = 2 * 3 = 6 joules

Gain in potential energy = 0 joules

Answer 2

W=6 J (Joules)

Ep=0 J (Joules)

Explanation:

A trunk is dragged 3 m across an attic floor by a force of 2 N.

Work done is the amount of energy transferred. The formula is:

W=F×d

Which is the same as:

W=F×d=F.d.cosφ

Where,

F: Force (N).

d: Distance moved in the direction of the force (displacement) (m).

φ: Angle between the force and the direction of motion.

Now, replacing the data:

W=2N.3m.cos(0°) (We assume that the force and the displacement have the same direction and orientation. That's why φ=0°)

Then,

W=2N.3m.1=6Nm

W=6 J

Now we have to calculate the gain in potential energy:

The gravitational potential energy (Ep) is the energy stored by an object because of its position. The formula is:

Ep=m.g.h

Where,

m: Mass of the object. (Kg)

g: Acceleration due to gravity. (
`(m)/(s^2)`)

h: Vertical height. (m)

In this case there isn't vertical height. We assume that the displacement is in the floor level and we are going to take this as h=0m

Ep=0 J