Weight Component: Find Force Components for Box on Inclined Surface

In summary, the weight force acting on the box is mgcos(30) when perpendicular to the surface and mgsin(30) when parallel to the surface. The components of the weight force are the magnitude of the legs of a right triangle, one leg parallel to the sliding surface and the other perpendicular to it.
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Homework Statement


Well I am trying to get help on weight compent. It is a box sliding on an inclined surface with angle 30 degrees.


Homework Equations



w= mg

The Attempt at a Solution



I am trying to find the components for weight force acting on the box. Book says w=mgcos(30) is when its perpendicular to surface, and w= mgsin(30) when its parallel to surface. Can someone explain how to do this?
Thanks
 
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  • #2
I am trying to find the components for weight force acting on the box. Book says w=mgcos(30) is when its perpendicular to surface, and w= mgsin(30) when its parallel to surface. Can someone explain how to do this?
Thanks
spdowind,welcome to PF! Are you familiar with the method for calculating vector components by drawing a right triangle? Draw a sketch. The weight force acts straight down vertically...that's the hypotenuse of the right triangle. The components are the magnitudes of the legs of that right triangle, one leg parallel to the plane surface, and the other perperpendicular to it. You'll have to do a little geometry and some basic trig to calculate these components. Please show some attempt at this for further assistance.
 
  • #3
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See i am trying to find the horizontal forces for the block sliding down.
I did:
Fx= m* ax
mg*sin(angle)- Tension force - Friction Force= mass * Acceleration.

I just don't understand why I use mg* sin ( angle) instead of mg*cos(angle) when I do the weight x-component minus tension force and friction force.
 
  • #4
well from my understand again,my graph is a lil off the angle is wrong.
What I do understand is:

The weight is split into 2 components like my graph, but one is horizontal to the sliding surface , one is perpendicular to it, the one horizontal is the X compoent, which means parallel to surface means mgsin(angle)? Am I on the right track? Because I set up my x-y coordinates horizontal to sliding surface and perpendicular to surface.

Thanks
 

What is weight component?

Weight component is the amount of force exerted by an object due to its mass and the acceleration of gravity. It is a vector quantity that is typically represented by the symbol "W" and measured in Newtons (N) or pounds (lbs).

How do you find force components for a box on an inclined surface?

To find the force components for a box on an inclined surface, you will need to use trigonometry. The weight component of the box can be broken down into two components: the perpendicular force (normal force) and the parallel force (parallel to the surface). The normal force can be found by multiplying the weight of the box by the cosine of the angle of inclination. The parallel force can be found by multiplying the weight of the box by the sine of the angle of inclination.

What is the normal force?

The normal force is the force that a surface exerts on an object in contact with it. It is always perpendicular to the surface and acts in the opposite direction of the force that the object exerts on the surface. In the case of a box on an inclined surface, the normal force is equal to the perpendicular force component of the weight.

What is the parallel force?

The parallel force is the component of a force that is parallel to a given surface. In the case of a box on an inclined surface, the parallel force is equal to the parallel force component of the weight. It is responsible for the box's motion down the incline.

How does the angle of inclination affect the force components?

The angle of inclination affects the force components by changing the ratios of the perpendicular and parallel components of the weight. As the angle increases, the parallel component increases and the perpendicular component decreases. At a 90 degree angle of inclination, the perpendicular component becomes zero and the parallel component becomes equal to the weight of the object.

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