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Find the force of Friction and minimum coefficient of friction

Problem Statement
A 50.0 kg person is walking horizontally with a constant acceleration of 0.25 m/s2 inside an elevator. The elevator is also accelerating downward at a rate of 1.0 m/s2. Find the force of friction between his shoes and the elevator. What minimum coefficient of friction between his shoes and the floor would make this scenario possible?
Relevant Equations
Fg = mg
Fn = mg-ma
Fnet = ma
Ff = u * Fn
Fg = mg
= 50 * 10
= 500 N

Fn = mg-ma
= 500 - (50.0)(1.0)
= 500-50
= 450

I don't necessarily know if this is right and I can't seem to find the Ff or coefficient of friction either. Please Help!
 

gneill

Mentor
20,488
2,610
You're normal force calculation is good. But you should show units on its result.

Now you need to find out what frictional force is required to achieve the stated horizontal acceleration. Knowing that, look to your fourth Relevant Equation. (For additional credit: is the frictional force Static or Dynamic?)
 

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