High School

A 120 N force is applied at an angle of 30.0 degrees above the horizontal to a 4.00 kg box. The box moves a horizontal distance of 8.00 meters.

The change in the kinetic energy of the box is:

A. 667 J
B. 750 J
C. 831 J
D. 890 J
E. 920 J

Answer :

The change in the kinetic energy of the box is c) 831 J.

To determine the change in the kinetic energy of the box, we need to calculate the work done by the applied force. The work done by a force can be found using the formula:

Work = Force × Distance × cos(θ)

Where:

  • Force = 120 N
  • Distance = 8.00 m
  • θ = 30.0 degrees

We need to calculate the component of the force in the direction of the displacement, which is Force × cos(30.0 degrees):

cos(30.0 degrees) = √3 / 2 ≈ 0.866

Thus, the effective force in the direction of the displacement is:

120 N × 0.866 ≈ 103.92 N

Now, we can calculate the work done:

Work = 103.92 N × 8.00 m ≈ 831.36 J

Therefore, the change in the kinetic energy of the box is approximately 831 J (option C).

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