A 200-N block,on a 30° incline,is being held motionless by friction.The coefficient of static friction between the block and the plane is 0.60.The force due to friction is:
A) 104 N.
B) 100 N.
C) 60 N.
D) 0 N.

Question

Quizplus · Accepted Answer

The force due to friction is given by the product of the coefficient of static friction and the normal force acting on the block. The normal force is equal to the component of the weight of the block perpendicular to the plane, which is given by:

N = mg cosθ = 200 N × cos30° ≈ 173.2 N

Therefore, the force due to friction is:

f_s = μ_s N = 0.60 × 173.2 N ≈ 103.9 N ≈ 100 N (to one significant figure)

Since the block is being held motionless by friction, the force due to friction must be equal and opposite to the component of the weight of the block parallel to the plane:

f_s = mg sinθ = 200 N × sin30° ≈ 100 N

Therefore, the correct answer is B) 100 N.

A 200-N Block,on a 30° Incline,is Being Held Motionless by Friction.The