Physics question about forces and normal force?

Question

What equation is used to calculate the Fn or normal force acting on an object that is on a slope?

Does it matter if the object is moving up or down the slope?

Answer 1

use :Fn=Fy

-you need to find Fy(force of gravity in the y direction) using the Fg(force of gravity)
:Fy=FgCos(theta)where theta = the angle above the horizon
(the angle at the bottom of the triangle if you drew it out)



i'm pretty sure your looking for the cosine, not the sine

Answer 2

First consider a horizontal plane.

Let the object of weight mg be on the plane.

The normal reaction is mg vertically upward.

Erect a vertical pole on the plane through the object.

This vertical pole represents the normal reaction.

Now tilt the plane through some angle Ө

The pole will also tilt through the same angle Ө.

That is the normal reaction has tilted through angle Ө.

The angle between the vertical line and the slanting pole is Ө.

The vertical direction is mg (the weight)

THE NORMAL REACTION IS ADJACENT TO Ө or to mg.

We know “cos” corresponds to adjacent side or angle.

Therefore the normal reaction is mg cos Ө.

Whether the object is moving up or down the normal reaction will always be the same.

Similarly the pulling force mg sin Ө will always act down the plane.

Friction will be acting up when the body comes down and will act down along with mg sin Ө, when the object moves up.

Answer 3

i sure hope that i could draw the diagram here

you see, your question is somehow vague but this is how i interpret it.

when you say that a normal force is acting on a slope (let's say 30 degree uphill) i immediately imagined that the angle from the normal force to the force of gravity pull is of course 30 degrees.

therefore we have the trigo:

cos@ = Fg / Fn

where:
@ = slope angle
Fg = gravitational force or weight of the object
Fn = normal force

so we have:
Fn = Fg / cos@

is this it?

Answer 4

If there is a body resting on a plane, the normal force is the force exerted by the plane on the body. It is called "normal" because the force is acting perpendicular to the body. By definition, Frictional force = coeff of friction * Normal force so, assuming a constant value of the coefficient of friction, the frictional force is directly proportional to the normal force. As the mass of the body is increased, the normal force also increases hence the frictional force also increases. The reverse is true as well. If the mass of the body is decreased, the normal force decreases, hence the frictional force decreases. Hope this helps.

Answer 5

Fn=(Fg)sinangle

Answer 6

Fnormal = Fweigh - sin(theta)Fapply

for example: a man is pull a 50kg sled at an angle of 30 degrees above the horizon with 100N

Fweigh=mg
Wweigh = (50kg)(9.8)
Fweigh=568.4N

Find the y-component of the Fapply
Fa(y) = sin(30)100= 50N

Fnormal = 568.4N - 50N
Fnormal = 518.4N