A 75-kg man rides an elevator which is accelerating upward with a uniform acceleration of 1.4 m/s².What is the maximum force of static friction if the coefficient of friction between him and the floor is 0.42? A)260 N B)310 N C)350 N D)840 N

Question

Quizplus · Accepted Answer

First, we need to find the normal force (N) acting on the man. Since the elevator is accelerating upward, the net force acting on the man is the force of gravity (mg) minus the force needed to accelerate him upward (ma):
Fnet = ma = (75 kg)(1.4 m/s^2) = 105 N
Fnet = mg - N
N = mg - Fnet = (75 kg)(9.81 m/s^2) - 105 N = 632.25 N

Next, we can find the maximum force of static friction (Fs) using the coefficient of friction (μ):
Fs = μN = (0.42)(632.25 N) = 265.16 N

Therefore, the closest answer choice is C) 350 N.

A 75-Kg Man Rides an Elevator Which Is Accelerating Upward