Calculating Work Done by Constant Force on Stubborn Pig: Homework Solutions

[Vanessa Avila]

Homework Statement

On a farm, you are pushing on a stubborn pig with a constant horizontal force with magnitude 34.1 N and direction 37.0∘counterclockwise from the +x-axis.

a) How much work does this force do during a displacement of the pig that is s⃗ =(5.00m)ι^?

b) How much work does this force do during a displacement of the pig that is s⃗ =−(6.00m)j^?

c) How much work does this force do during a displacement of the pig that is s⃗ =−(2.00m)ι^+(4.00m)j^?

Homework Equations

W = F*d

The Attempt at a Solution

I drew this out of the given problem but I'm not sure if it is right:

With that drawing I solved for
Fx = Nsin37.1 = 34.1sin37.1 = 20.7N
Fy = Ncos37.1 = 34.1cos37.1 = 27.2 N
Fr = 34.2 N

1.) At first i multiplied the resultant to 5m to get W but that didn't work. So I took the Fx = 20.7 and multiplied that to 5m but that didn't work either.

What to do?

 

[SammyS]

Homework Statement

On a farm, you are pushing on a stubborn pig with a constant horizontal force with magnitude 34.1 N and direction 37.0∘counterclockwise from the +x-axis.

a) How much work does this force do during a displacement of the pig that is s⃗ =(5.00m)ι^?

b) How much work does this force do during a displacement of the pig that is s⃗ =−(6.00m)j^?

c) How much work does this force do during a displacement of the pig that is s⃗ =−(2.00m)ι^+(4.00m)j^?

Homework Equations

W = F*d

The Attempt at a Solution

I drew this out of the given problem but I'm not sure if it is right:

With that drawing I solved for
Fx = Nsin37.1 = 34.1sin37.1 = 20.7N
Fy = Ncos37.1 = 34.1cos37.1 = 27.2 N
Fr = 34.2 N

1.) At first i multiplied the resultant to 5m to get W but that didn't work. So I took the Fx = 20.7 and multiplied that to 5m but that didn't work either.

What to do?

The problem states that the direction of the force is 37.0° counterclockwise from the positive x-axis.

Your sketch shows a force that's 37.1° clockwise from the positive y-axis.

That could cause an error .

 

[Vanessa Avila]

The problem states that the direction of the force is 37.0° counterclockwise from the positive x-axis.

Your sketch shows a force that's 37.1° clockwise from the positive y-axis.

That could cause an error .

Okay so it should be looking like this? :

 

[kuruman]

No. The positive x-axis is horizontal and points to the right. Start there and go counterclockwise 37.1^o.

 

[haruspex]

Okay so it should be looking like this? :

Further to kuruman's comment, please label the axes (+X, -X, +Y, -Y) to ensure no misunderstanding.

 

[SammyS]

Is some of the difficulty here caused by the overwhelming use of digital clocks these days ?