# An object attached by two strings on a vertical rod travels at a constant velocity

1. Jun 24, 2012

### StrawHat

1. The problem statement, all variables and given/known data

**Hope I don't get in trouble for posting a screenshot of this online homework question...**

2. Relevant equations
$\Sigma$Fx = marad = $\frac{mv^2}{r}$
$\Sigma$Fy = mg

3. The attempt at a solution
Simple equations allowed me to find r = 1.323m and θ = 41.41°
$\Sigma$Fx = Tuppersinθ + Tlowersinθ + mgsinθ = $\frac{mv^2}{r}$
Tuppersinθ + Tlowersinθ + 28.85N = 169.57N
Tupper + Tlower = 212.75N

$\Sigma$Fy = Tuppercosθ - Tlowercosθ - mg = 0
Tuppercosθ - Tlowercosθ = mg
Tupper - Tlower = 58.15N
Tupper = 58.15N + Tlower

Substituting Tupper,
58.15N + Tlower + Tlower = 212.75N
58.15N + 2(Tlower) = 212.75N
Tlower = 77.3N
Tupper = 58.15N + 77.3N = 135.45N

Last edited: Jun 24, 2012
2. Jun 24, 2012

### Staff: Mentor

Re: An object attached by two strings on a vertical rod travels at a constant velocit

Good.
In what direction does the weight act?

3. Jun 24, 2012

### StrawHat

Re: An object attached by two strings on a vertical rod travels at a constant velocit

Away from the pole, so I guess mgsinθ is negative as well?

EDIT: Ah, nope. Fx is only mv^2/r, so I don't need to take into account the gravitational force. Got the answers, thanks for your help!

Last edited: Jun 24, 2012