Calculating Work: Piano Lowering 5m, 2500N Gravity, T1 1830N, T2 1295N

[indietro]

Homework Statement

There is a piano that is being lowered 5 m. It has gravity force acting in y-direction (down) of 2500 N. Then it has two ropes attached, they are vectors that are pointing up and out. so T1 is 1830N [W60^$$\circ$$N] and T2 is 1295N [E45^$$\circ$$N]

Homework Equations

so the work by gravity is 12500 J
the work by T1 is 4575 J (opposite direction to work by gravity)

The Attempt at a Solution

so it would make sense that the work by T2 is somewhere close to 7000 J so that the net work is 0. but when i calculate it i get around 4000 J. Can someone check my math...

For T2:
W = Fcos$$\theta$$$$\Delta$$r
= 1295*cos45*(5)
= 4579 J

? - thnx!

 

[fatra2]

Hi there,

I believe you have a problem with the angle of T1. Becausem, when I verified your calculations, I come to precisely 0 net work.

Cheers

 

[indietro]

oh yes thank you! i was using an angle that gave the component perpendicular to motion :)