Find the force of Friction and minimum coefficient of friction

  • #1

Homework 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!
 

Answers and Replies

  • #2
gneill
Mentor
20,813
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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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