Physics Friction Homework: Normal Force on 80kg Object

[Intrusionv2]

Homework Statement

Find the normal force on an object, 80kg, which is being pulled up by a force of 4000N at an angle of: A) Up at 50 degrees. B) Down at an angle of 70 degrees.

Homework Equations

Fw = mg
Fsinx
Fcosx

The Attempt at a Solution

A) Fn = 784 - 4000sin50 = -2280 = 2280N


B) Fn = 784 + 4000sin70 = 4543N

Is this correct?

 

[septum]

part B would have to be sin(-70) since it is below, correct?

 

[Intrusionv2]

But did you notice that I added instead of subtracted the 2nd one?

 

[septum]

Okay, well as I understand it for part A normal force is equal to mgcos50 degrees. I don't think you have to multiply anything but gravity by your mass.

Thus, n=mgcos: n=(80kg)(9.8 m/s^2)*cos(50)

 

[Intrusionv2]

It is not on an incline. it is being pulled up at an angle.

 

[septum]

I can't picture anything being pulled up at an angle without being on an incline so I'm probably not the person to be trying to help. :/ Sorry

 

[Sonolum]

Have you tried drawing a free body diagram? What is the Normal force equal to? In part (a), is the pulling increasing or decreasing the normal force? In part (b) is the pulling increasing or decreasing the normal force?