The magnitude of the normal force exerted on the block by the plane is most nearly

Question

A plane 5 meters in length is inclined at an angle of 37°, as shown. A block of weight 20 newtons is placed at the top of the plane and allowed to slide down.

The magnitude of the normal force exerted on the block by the plane is most nearly 

(A) 10 N 

(B) 12 N 

(C) 16 N 

(D) 20 N 

(E) 33 N

Answer 1

Correct option (C) 16N  

F_n = F_gy = mg cos θ.

Since you are given the incline with sides listed, cos θ can be found by using the dimensions of the incline … cos θ = adj/hyp = 4/5 to make math simple. This is a good trick to learn for physics problems.