Physics help

[thescreensavers]

A person Pulling a car along a level road with a rope must exert a force of 90 pounds. How much work is done in moving the cart 120 feet, if the rope makes and angle of 27 deg with the road.

W= T x D?

How would you solve this? I have no clue.

 

[Locut0s]

Find the component of the force that is parallel with the car's motion.

 

[GodlessAstronomer]

Remember your trigonometry? Forces work in components just like distances and velocities. Find the components of force in the x and y axis, the rest should fall into place.

 

[thescreensavers]

^ lol what? Seriously ???

 

[Leros]

^ lol what? Seriously ???

This is basic basic basic physics.

 

[Jeff7]

This is basic basic basic physics.

Well....there's something else to consider: We've got varying age groups here, and varying levels of exposure to this kind of stuff. It may be basic basic physics, but for some, that's all they've ever been taught thus far.

So then...

Thescreensavers: What level physics is this? As in, what class are you in? How much physics background do you have at this point? Have you ever drawn a free-body-diagram before?

 

[thescreensavers]

well actually I figured it out, hope its right lol.

90(cos 27 i + sin 27 j )

(80.2 i+ 40.86 j)

80.2 (120) + 40.86(0) = 9624

I followed some video, but it seems wrong lol
9624 ft/lbs is what I got, its still prob wrong lol

 

[dighn]

well actually I figured it out, hope its right lol.

90(cos 27 i + sin 27 j )

(80.2 i+ 40.86 j)

80.2 (120) + 40.86(0) = 9624

I followed some video, but it seems wrong lol
9624 ft/lbs is what I got, its still prob wrong lol

looks right to me. but physics in non-metric = fail

 

[GodlessAstronomer]

^ lol what? Seriously ???

??

Is there something wrong with my advice? I wrote it in kind of a hurry.

 

[Jeff7]

??

Is there something wrong with my advice? I wrote it in kind of a hurry.

Looks fine to me.

 

[thescreensavers]

??

Is there something wrong with my advice? I wrote it in kind of a hurry.

oh its fine I just was reading it as Chinese at the time. The answer I came up with was correct?

 

[Hacp]

Shouldn't the answer be simple?
120*90*cos27.

You only need to worry about IJK if you're doing dot/cross products in 3 dimensions I think.

 

[yhelothar]

The forumla is
Work(Nm) = Force(N)) × Distance(m)

w=fd

 

[Ken g6]

120*90*cos27.

Looks right. But 120*90*cos27 *what*? Pink elephants?

You should always work it through with units included. That way if you wind up with pink elephants (or 1/s^2 or something) instead of the units you expected in the result, you know something's amiss.

120 ft*90 lb*cos27 degrees = x ft*lb