How do you find the normal force of an object being pushed?

[Maya KDeoimmich]

Homework Statement

A 42 kg wagon is being pushed with a metal rod that makes an angle of 46 with the horizontal. The applied force is 449 N and the coefficient of kinetic friction between the wagon and the ground is 0.21.
I'm not sure what equation to use to find the normal force and then the acceleration. Thanks!

Homework Equations

Fy = mgcos46-N

The Attempt at a Solution

 

[Doc Al]

I'm not sure what equation to use to find the normal force and then the acceleration.

You'll use Newton's laws, of course.

First step: What forces act on the wagon? (I count three forces.)

 

[Maya KDeoimmich]

Ok thanks but can you please walk me through the steps of how to find the normal force and the acceleration

 

[Doc Al]

First answer my question. What forces act on the wagon?

 

[Maya KDeoimmich]

Gravity, friction, and the applied force

 

[Doc Al]

Gravity, friction, and the applied force

Oops, one more force acts. (I meant to say four, not three.) But those three are good. What's missing?

 

[Maya KDeoimmich]

normal force? not sure

 

[Doc Al]

normal force? not sure

Exactly.

Now you'll set up two equations: One for vertical forces (vertical components) and another for horizontal forces.

Hint: What must the sum of the vertical forces equal?

 

[haruspex]

an angle of 46 with the horizontal

Which way? I.e. is it tending to push down on the wagon or up on it?

Fy = mgcos46-N

How do you get that? Isn't the mg vertical?

the coefficient of kinetic friction between the wagon and the ground is 0.21

Ouch! Unless the wheels are locked they mean rolling resistance, not friction, but don't worry about that for now.