A block of mass m is pulled along a rough horizontal floor by an applied force as shown. The vertical component of the force exerted on the block by the floor is:
A) mg
B) mg - T cos $\theta$
C) mg + T cos $\theta$
D) mg - T sin $\theta$
E) mg + T sin$\theta$

Question

A block of mass m is pulled along a rough horizontal floor by an applied force  as shown. The vertical component of the force exerted on the block by the floor is: 
A) mg 
B) mg - T cos $\theta$ 
C) mg + T cos $\theta$ 
D) mg - T sin $\theta$ 
E) mg + T sin$\theta$

Quizplus · Accepted Answer

The vertical component of the applied force is cancelled by the normal force exerted by the floor on the block. Therefore, the only vertical forces acting on the block are the weight (mg) and the vertical component of the tension force (T sinθ). The net vertical force acting on the block in the upward direction is then:
Fn = T sinθ - mg.
Therefore, the correct answer is D, which is mg - T sinθ.

A Block of Mass M Is Pulled Along a Rough θ\thetaθ

A Block of Mass M Is Pulled Along a Rough $\theta$