Question

Quiz Revisions:
Bored during the Pandemic, you decided that this would be the perfect time to redesign your
kitchen AND practice physics. So you push your fridge. Your fridge has a mass of 150 kg and
the coefficient of kinetic friction between your fridge
and the ground is.35. You
push the fridge
with a force of 600 N. You push the fridge a distance of 5 m.
1. What is the frictional force the fridge experiences?
Student Response: The fridge experiences a frictional force of .35.
Why is this student incorrect? What should the answer be?

Answer 1

Answer:

fr = 514.5 N,    This force has the opposite direction to the applied force.

Explanation:

Let's propose the solution of the problem using Newton's Second Law, we place a reference frame with the horizontal x-axis

Y axis

         N- W = 0

         N = W

X axis

         F -fr = m a

         

the friction force has the expression

        fr = μ N

        fr = μ mg

       

        fr = 0.35  150  9.8

        fr = 514.5 N

This force has the opposite direction to the applied force.

The student's answer is incorrect because the friction coefficient must be multiplied by the normal