A 280 N force is pulling an 80.0 kg refrigerator across a horizontal surface. The force acts at an angle of 18.0° above the surface. The coefficient of kinetic friction is 0.200, and the refrigerator moves a distance of 8.00 m.

(a) Find the work done by the pulling force.

(b) Find the work done by the kinetic frictional force.

To answer both parts of the question, we need to use the formula for work, which is given by:

Work = Force * Distance * cos(θ)

where:
- Force is the magnitude of the force being applied
- Distance is the distance over which the force is applied
- θ is the angle between the force and the direction of motion

(a) To find the work done by the pulling force, we'll use the given force of 280 N and the distance of 8.00 m. The angle θ is 18.0°. We'll convert the angle to radians:

θ = 18.0° * (π/180) ≈ 0.314 radians

Now, we can calculate the work done by the pulling force:

Work = 280 N * 8.00 m * cos(0.314)
Work ≈ 2093.4 Joules

Therefore, the work done by the pulling force is approximately 2093.4 Joules.

(b) To find the work done by the kinetic frictional force, we'll first need to calculate the magnitude of the frictional force. The formula for the magnitude of the frictional force is:

Frictional force = coefficient of friction * normal force

The normal force is equal to the weight of the refrigerator, which can be calculated by multiplying the mass (80.0 kg) by the acceleration due to gravity (9.8 m/s^2):

Normal force = 80.0 kg * 9.8 m/s^2 ≈ 784 N

Now, we can calculate the frictional force:

Frictional force = 0.200 * 784 N ≈ 156.8 N

The frictional force acts in the opposite direction to the motion, so the angle between the force and the direction of motion is 180°. We can now calculate the work done by the kinetic frictional force:

Work = -156.8 N * 8.00 m * cos(180°)
Work ≈ -1254.4 Joules

Note that we have a negative sign in front of the work done because the frictional force opposes the motion, and work done against the frictional force is considered negative.

Therefore, the work done by the kinetic frictional force is approximately -1254.4 Joules.