Explain the coefficient of kinetic friction, the work-energy theorem, and draw a free-body diagram for an object being pulled by a force at an angle.

Question 5

5.1:
The coefficient of kinetic friction is a ratio of two forces: the kinetic frictional force and the normal force. Since it is a ratio of quantities with the same units (Newtons), the units cancel out, making the coefficient dimensionless.

5.2:
The work-energy theorem states that the net work done on an object is equal to the change in its kinetic energy.

5.3:
Free-body diagram:

• Applied Force ($F$): At an angle of $20^\circ$ above the horizontal.
• Gravitational Force ($F_g$): Vertically downwards.
• Normal Force ($F_N$): Vertically upwards, perpendicular to the surface.
• Kinetic Frictional Force ($f_k$): Horizontally opposite to the direction of motion.

5.4:

Step 1: Determine the normal force ($F_N$).
The sum of forces in the vertical direction is zero because there is no vertical acceleration.

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