(c) Determine the friction force exerted on the block (assumed to be constant).

To determine the friction force exerted on the block, you need to follow these steps:

1. Identify the mass of the block and the coefficient of friction. These values are usually given in the problem.

2. Calculate the weight of the block. This can be done by multiplying the mass of the block by the acceleration due to gravity. The standard acceleration due to gravity is approximately 9.8 m/s². So, if the mass of the block is m, the weight (W) would be m * 9.8.

3. Calculate the normal force (N). For an object on a flat surface, the normal force is equal to the weight of the object. So, N = W.

4. Finally, calculate the friction force (F). The friction force can be found by multiplying the normal force by the coefficient of friction (μ). So, F = μ * N.

Remember, this calculation assumes that the friction force is constant and the surface is flat. If the surface is inclined or the friction force varies, the calculation would be different.