Two different people push a fridge at two different times. Find Ffric and mass.

[G-S]

I honestly can't figure out what to do.

3. Paul and Mintu are attempting to push a heavy fridge across the kitchen floor. When Paul pushes it with a muscular force of 550N, the fridge accelerates from rest to 28.0 cm/s in 3.5 s. When Mintu pushes it with a muscular force of 560N, the fridge accelerates from rest to 36 cm/s in 3.0 s. Calculate the force due to friction and the mass of the fridge.

 

[PhanthomJay]

You should start by examining the forces acting on the fridge. Then set up equations in the horizontal and vertical directions for each case, and apply Newton's laws. What are the forces acting on the fridge?

 

[G-S]

Well I know there is an applied force and the force of friction working against it, but do i count in the force of gravity? And I don't see the reason why there are two different people, aren't the force due to friction and the mass going to stay the same no matter who pushes it?

 

[rakbarut]

What you need to do is split the problem into two parts (Paul's part and Muntu's part). For paul's part, sum the forces on the refrigerator and solve for the mass. This answer should have the coefficient of friction within it, but that's okay. Okay once you have the what the mass is equal to, sum the forces on the refrigerator when mintu pushes it. Then plug in what you have for the mass everywhere mass is in the equation and then solve for the coefficient of friction. Then, use that coefficient to find the mass (plug it into the answer you got in part one). Once you have the mass, you can easily calculate the force of friction...
If you have any questions, let me know!

 

[rakbarut]

sorry for interrupting, while I was typing you guys must have posted...

 

[G-S]

Thanks! I understand what to do now, its just basic substitution. Your post helped a lot!