Question Detail
Question
A 2.0 kg block is pressed against a rough vertical wall by a horizontal force F. If the coefficient of static friction between the block and the wall is 0.2, the smallest value of F to prevent the block from sliding down (g=10 m/s²) is:
Correct Answer
Option C is the correct answer.
Detailed Explanation
To prevent the block from sliding, the frictional force f must equal its weight mg. Since f = μs N, and in this case the normal force N is equal to the applied horizontal force F, we have μs F = mg. Therefore, F = mg/μs = (2.0 kg * 10 m/s²) / 0.2 = 100 N.
Hint
The normal force here is provided by the horizontal push F.