# Gravitational force on inclined plane

#### Joe91090

1. Homework Statement

You place a box weighing 265.5N on an inclined plane that makes a 43.2 degree angle with the horizontal. Compute the component of the gravitaltional force acting down on the inclined plane.

2. Homework Equations

m x g x cos(degree)

3. The Attempt at a Solution

265.5 x 9.8 x cos(43.2)

The answer came out incorrect. I think I calculating the wrong force the question confuses me.

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#### Dr.D

Re: Forces

Try drawing the picture. You need to think the geometry through rather than just trying to plug numbers into formulas.

#### Joe91090

Re: Forces

still very confused do you mean a free body diagram ?

#### Dr.D

Re: Forces

An FBD should do the job. Perhaps you are confused by the wording. The words, "component ... acting down on the inclined plane" refers to the force normal (perpendicular) to the plane.

#### Joe91090

Re: Forces

So wouldnt the Normal force be the same as the mass because the inclined plane is holding it up ?

#### Dr.D

Re: Forces

Which direction is the weight?

Re: Forces

straight down ?

#### lubuntu

Re: Forces

since when is mass measured in newtons?

#### Joe91090

Re: Forces

thats what im saying wouldnt the Normal force be W=mg ?

#### Joe91090

Re: Forces

ok so.. 265.5 = m 9.8

m = 27.1N

27.1 x 9.8 x cos(43.2) = 193.6 N = Fn ????

#### carrotcake10

Re: Forces

m = 27.1N
Newton's aren't a unit of mass

Otherwise, it looks ok to me.

#### Joe91090

Re: Forces

193.6N isnt the correct answer im still stumped

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