# Homework Help: Physics help -- pushing a refrigerator across a wooden floor

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1. Oct 8, 2014

### mememe1245

Joe is moving his refrigerator to take to college and he begins by pushing it across
the wooden kitchen floor.

On a flat surface like the floor, how do you calculate how hard he needs to push?

Draw a free body diagram to help explain your answer and use the simulation Ramp:
Force and Motion to check your ideas.
1.Record the minimum force Joe would have
to use to move the refrigerator on the kitchen floor.

2. Later, Joe is ready to load his refrigerator onto the moving truck.

a. Explain how he would calculate how much force to use to lift the refrigerator straight
up into a truck.

b. Joe starts thinking about easier ways to get it in the truck and remembers he has

some wood that he could use to make a ramp. How could he calculate the minimum

force needed to push it up the ramp?

-------------
Sorry I've been stuck on this for an hour :(

By using these...:
(kinetic/ sliding) mu=0.2
mass= 200kg
Normal Force= 2000N

Last edited: Oct 8, 2014
2. Oct 8, 2014

### lightbender

Do you know the refrigerator's mass?

3. Oct 8, 2014

200 kg

4. Oct 8, 2014

### lightbender

So, first you would calculate the gravitational pull: G=gm, where g=9.8m/s

5. Oct 8, 2014

### mememe1245

G= 200kg * 9.8m/s^2 = 1960N?

6. Oct 8, 2014

### lightbender

Oh, wait! I did not see that you changed your original thread!
Actually, first since the normal force is 2000N, the gravitational force is also 2000N.

7. Oct 8, 2014

Okay...

8. Oct 8, 2014

### lightbender

Then, to find the sliding friction force, you would do: Sliding=normal force x mu

9. Oct 8, 2014

### mememe1245

so, mu=force of friction/ force of newton, right?

10. Oct 8, 2014

### lightbender

11. Oct 8, 2014

### mememe1245

Okay, I understand that mu = .2 and g= 2000N. What I don't understand is how to solve the problem.

12. Oct 8, 2014

### lightbender

So, you just multiply them together resulting in the numerical value for sliding friction

13. Oct 8, 2014

### mememe1245

Ohhh...Waw! Thank u!

14. Oct 8, 2014

### lightbender

The sliding friction answer is the equivalent to the minimum force needed to push the refrigerator! (answer in Newtons)