Crate pushed up an inclined plane

[rrosa522]

Homework Statement

A warehouse worker pushes a crate of mass 24 kg up a ramp. Assume that the friction between the crate and ramp can be ignored.
a) Determine the component of gravitational force directed along the ramp's surface.
b) Calculate the force required to move the crate at a constant speed up the ramp.
c) Calculate the work done in pushing the crate 23 m as measured along the ramp. Assume the crate moves at a constant velocity.
d) Assume the coefficient of kinetic friction between the crate and the ramp is μk = 0.25. Calculate the work done on the crate by the worker and by friction, and calculate the total work done as the worker pushes the crate 16 m up the ramp.

Homework Equations

The Attempt at a Solution

for (a) I got 235N (just multiplied mass by 9.81) but the answer is 120N

 

[Doc Al]

I got 235N (just multiplied mass by 9.81)

That would be the crate's weight. But they are asking for a component of the weight. (What angle does the ramp make with the horizontal?)

 

[rrosa522]

That would be the crate's weight. But they are asking for a component of the weight. (What angle does the ramp make with the horizontal?)

30 degrees

 

[Doc Al]

30 degrees

OK. Now draw yourself a diagram. Use it and a little trig to find the components of the weight parallel and perpendicular to the incline.

 

[ava ray]

And if you do that:
fgx=fgcos30
=(24)(9.8)cos30
=203.69N

but it says the correct answer is 120N, am I doing something wrong, this seems pretty basic but idk.

 

[Doc Al]

And if you do that:
fgx=fgcos30
=(24)(9.8)cos30
=203.69N

but it says the correct answer is 120N, am I doing something wrong, this seems pretty basic but idk.

You found the component of the weight perpendicular to the plane, but they want the component parallel to it.

 

[ava ray]

whoops I have to use sin
just noticed thanks