Question

Use the work energy theorem to rank the final kinetic energy of a ball based on the initial kinetic energy Ki, the magnitude of a constant force F on the ball, the displacement of the ball, d and the angle, theta between the displacement of the ball and the net force on the ball. Rank from greatest kinetic energy (1) to least kinetic energy (4).

a) Ki=150J F=10N d=15m theta=90 degrees
b) Ki=300J F=200N d=1.5m theta=180 degrees
c) Ki=200J F=25N d=4m theta=0 degrees
d) Ki=450J F=15N d=30m theta=150 degrees​

Answer 1

Step-by-step explanation:

The work-energy theorem states that the net work done on an object is equal to its change in kinetic energy. Therefore, we can use this theorem to calculate the final kinetic energy of the ball in each case.

We know that the work done by a constant force is given by the equation W = Fd cos(theta), where F is the magnitude of the force, d is the displacement of the ball, and theta is the angle between the force and displacement vectors.

Using the work-energy theorem, we can write:

W = ΔK = Kf - Ki

where ΔK is the change in kinetic energy, Kf is the final kinetic energy, and Ki is the initial kinetic energy.

We can rearrange this equation to solve for Kf:

Kf = Ki + W = Ki + Fd cos(theta)

a) Kf = 150 J + (10 N)(15 m)cos(90°) = 150 J

b) Kf = 300 J + (200 N)(1.5 m)cos(180°) = 0 J

c) Kf = 200 J + (25 N)(4 m)cos(0°) = 300 J

d) Kf = 450 J + (15 N)(30 m)cos(150°) = 112.5 J

Ranking from greatest to least final kinetic energy:

c) Ki=200J F=25N d=4m theta=0 degrees

a) Ki=150J F=10N d=15m theta=90 degrees

d) Ki=450J F=15N d=30m theta=150 degrees​

b) Ki=300J F=200N d=1.5m theta=180 degrees