A pendulum is 0.8 m long and the bob has a mass of 1.0 kg. At the bottom of its swing, the bob's speed is 1.8 m/s. What is the tension in the string at the bottom of the swing?
2007-09-25 12:39:24 · 2 answers · asked by hehasnoidea2001 2 in Science & Mathematics ➔ Physics
You need to take two forces into account:
1. The weight of the pendulum
2. The centripetal force caused by the rotational movement of the pendulum.
The weight of the pendulum will result in a force:
w = m*g
which will give 9.81N
The centripetal force will be equal to:
F = m*r*w^2 where w is actually Greek letter omega.
We have m = 1kg and r = 0.8m, however w is unknown.
Converting the bob's speed from 1.8m/s to rad/s:
v = r*w
Therefore w = 1.8 / 0.8 = 2.25 rad/s
So F = 1 * 0.8 * 2.25^2 = 4.05 N
Summing the two:
Tension = Weight + Centripetal Force
Tension = 9.81 + 4.05 = 13.86N
2007-09-26 09:25:57 · answer #1 · answered by bassdude_46 2 · 0⤊ 0⤋
The tension is m*g plus the centriptal force
m*v^2/r
or
m*(g+v^2/r)
j
2007-09-26 14:01:17 · answer #2 · answered by odu83 7 · 0⤊ 0⤋