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A block of a mass m = 2.1 kg is pushed up against a vertical wall by a force F.

ID: 1540426 • Letter: A

Question

A block of a mass m = 2.1 kg is pushed up against a vertical wall by a force F. The angle is 40 degrees. The coefficient of static friction between the block and the wall is 0.5. Find the minimum force F, in N, that would keep the block from sliding. Infinite 41 42 20. 0 A person lets go of a rope. A crate slides down a slope with an angle of inclination of 30 degrees. The coefficient of moving friction between the crate and the slope is 0.2. How fast, in m/s, is the crate going after it moves 2m? 1 13 5.1 3.6. 36 An empty elevator, M = 100kg. has a counter weight m

Explanation / Answer

here,

mass , m = 2.1 kg

theta = 40 degree

us = 0.5

the normal force on wall , N = F * cos(theta)

for the block not to slide

m * g = us * N + F * sin(theta)

m * g = us * F * cos(theta) + F * sin(theta)

2.1 * 9.8 = 0.5 * F * cos(40) + F * sin(40)

solving for F

F = 20 N

the net force applied is D) 20 N