Answer to Question #155772 in Molecular Physics | Thermodynamics for Eddy

Question

A 6-kg block lies on an inclined plane that slopes at 30 degrees to the horizontal. Determine the external force applied on the block parallel to the slope that causes the block to accelerate at 2 m/s² down the slope. Assume that the coefficient of kinetic friction between the block and the plane is 0.2.

Answer 1

Solution :

Assuming the force is up the slope, then Newton's Second gives

6kg*2$(\tfrac{m} {s^2 })$= 6kg*9.8$(\tfrac{m} {s^2 })$ *(sin30º - 0.2*cos30º) - F

F = 7.2 N

Since the result is positive, the assumption "up the slope" was correct.