Skateboard Press
Uniform circular motion downward force?
An 80kg man is skateboarding on frictionless ground at a constant speed of 7.5m/s . He grabs onto a 5m rope attached to a post at a 30 degree angle. With what force does his skateboard press against the ground?
Picture because I’m not sure even I understand what I just wrote.
http://tinypic.com/r/2zhe621/7
An 80kg man is skateboarding on frictionless ground at a constant speed of 7.5m/s . He grabs onto a 5m rope attached to a post at a 30 degree angle. With what force does his skateboard press against the ground?
Since the velocity = 7.5 m/s, radius = 5 m, and mass = 80 kg
Centripetal force = m * v^2 ÷ r = 80 * 7.5^2 ÷ 5 = 900 N
The Centripetal force is produced by the horizontal component of the tension in the rope, since there is no friction.
horizontal component of the tension = T * cos 30˚
T * cos 30˚ = 900 N
T = (900 ÷ cos 30˚) N
The vertical component of the Tension supports part the weight of the man
vertical component of the Tension = T * sin 30˚ = (900 ÷ cos 30˚) * sin 30˚ =
Weight of man = 80 * 9.8 = 784 N
The vertical component of the Tension supports [(900 ÷ cos 30˚) * sin 30˚] N
With what force does his skateboard press against the ground?
784 N – [(900 ÷ cos 30˚) * sin 30˚] N =
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