- #1
Nytrox
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Homework Statement
In the device shown below, a 1.75 kg ball suspended by two cords is whirled around in a circle of radius 95 cm. The ball makes 10 revolutions in 2 seconds. Find the tension in each of the two cords (remember: the tension in each cord acts toward the pole).
https://www.physicsforums.com/attachments/29633
Well...the attachment isn't quite working...so I'll attempt to draw the picture...
|..\ <--This angle 30 degrees
|...\ <--Cord 1
|...\
|...O <- Ball.....Radius from ball to pole = .95 meters (95 cm)
|.../......Angle of cords are both 30 degrees from the pole.
|.../ <--Cord 2.....Mass of ball is 1.75 kg
|.../
|.../ <--This angle 30 degrees
|./
^
Pole
Homework Equations
Fc = mV^2/r
Vt=2pi r/T
Fg=mg
F=ma
Ftx=Ftsin theta
Fty=Ftcos theta
The Attempt at a Solution
r=.95m
T=.2 seconds
Fty1-Fty2=Fg
Ft1cos30 - Ft2cos210 = 1.75kg x 9.8 m/s^2
Ft1+Ft2=19.8
Ftx1+Ftx2=Fc
Ft1sin30 + Ft2sin210 = m((2 pi r)/T)^2 / r
.5Ft1 - .5Ft2 = 1.75kg x (29.85 m/s)^2 / .95m
.5Ft1 - .5Ft2 = 1640.82N
Ft1 - Ft2 = 3281.64N
Ft1 = 19.8 - Ft2
19.8 - 2Ft2 = 3281.64N
Ft2 = -1630.92N
Ft1 = 1650.72N
I'm not sure if what I did is completely right. Please help. Thanks!