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Find the normal force on an inclined plane.

  • #1

Homework Statement


Find the normal force acting on a mass of 5kg on an incline plane of 30 degrees.


Homework Equations


Fn = mgsin30 or mgcos30 ?


The Attempt at a Solution


I'm not sure if I use sin or cos when finding the normal force on an incline. I have trouble visualizing the angle perpendicular to the plane and moving the angles around.
 

Answers and Replies

  • #2
Redbelly98
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Welcome to Physics Forums.

If the surface makes an angle θ to the horizontal, then the normal makes the same angle θ from the vertical. Does that help your visualizing?

If it's still unclear, think about a horizontal surface, so that θ is zero, and answer these questions:

1. What is the normal force when the surface is horizontal? Draw a force diagram for yourself, if you need to, to figure this out.

2. Does your answer to (1) agree with mgsin0 or mgcos0?

Hope that helps!
 
  • #3
It works with mgsin theta, but when i try to draw it out it doesn't make sense to me.
 
  • #4
Doc Al
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