Friction of an object being pulled up/down

  • Thread starter Intrusionv2
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    Friction
In summary: So yes, your equations are correct for the given scenario.In summary, when an 80kg object is being pulled at a force of 4000N at angles of 50 and 70 degrees, the normal force will be 503.9N and 268.14N, respectively.
  • #1
Intrusionv2
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Homework Statement


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

Homework Equations


Fn = Fwcosx
Fp = Fwsinx

The Attempt at a Solution



A)
Fp = Fwsinx
Fp = 4000sin50 = 3064N
(80*9.8) - 3064 = -2280N = 2280N

B)
Fp = 4000sin70 = 3758.8N
(80*9.8) + 3758.8 = 4542.7N

Is this correct?
 
Last edited:
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  • #2
I'm confused. Is the object being pulled up an inclined plane, or is it on a flat surface and the applied force acts at the given angles?
 
  • #3
Pulled up on an inclined plane.
 
  • #4
In that case your "Relevant Equations" are wrong. You need to draw a free body diagram and apply Newton's 2nd law to it. That's how you do every inclined plane problem.
 
  • #5
Tom Mattson said:
In that case your "Relevant Equations" are wrong. You need to draw a free body diagram and apply Newton's 2nd law to it. That's how you do every inclined plane problem.

Ah...I believe I was doing the other scenario then. In that case, I would simply do Fn = 80 * 9.8 * cos 50 = 503.9 N and Fn = 80 * 9.8 * cos70 = 268.14N, correct?
 
Last edited:
  • #6
The other scenario doesn't make much sense. If you pull on an 80 kg object with 4000 N at 50 degrees, the object will be lifted right off the ground. Hence, no normal force.
 

1. What is friction and how does it affect an object being pulled up/down?

Friction is a force that resists the motion of an object when it is in contact with another surface. When an object is being pulled up or down, friction acts in the opposite direction, making it harder to move the object.

2. How does the weight of the object affect the friction when being pulled up/down?

The weight of an object affects the friction because the heavier the object, the more force is needed to overcome the friction and move the object. This is why it may be more difficult to pull up or down a heavier object compared to a lighter one.

3. Does the type of surface the object is on affect the friction when being pulled up/down?

Yes, the type of surface the object is on can greatly affect the friction when being pulled up or down. Rough surfaces create more friction compared to smooth surfaces, making it more difficult to move the object.

4. How does the angle of the pull affect the friction when pulling an object up/down?

The angle of the pull can affect the friction because the steeper the angle, the more friction is created. This is because the weight of the object is now acting in a more downward direction, increasing the force needed to overcome the friction and move the object.

5. Is there a way to reduce friction when pulling an object up/down?

Yes, there are a few ways to reduce friction when pulling an object up or down. One way is to use a lubricant on the surface the object is on, such as oil or grease. Another way is to use wheels or rollers to help the object move more smoothly. Additionally, reducing the weight or changing the angle of the pull can also help reduce friction.

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