A bob on a string moves in a horizontal circle, tracing out a cone. The vertical part of the tension supports the weight, while the horizontal part provides the centripetal force. Spin it faster and watch the angle to the vertical grow as the cone opens.
MissionChange the rate of spin, then predict what happens to the angle θ as the bob is made to spin faster.Streak 0Best 0
As the bob is made to spin faster (larger ω), the angle θ to the vertical:
angle to vertical θ61°
radius r = L sinθ0.87 m
speed v = rω3.9 m/s
tension T = mg / cosθ4.0 N
period = 2π/ω1.4 s
cosθ = g / (Lω²), so a larger ω gives a smaller cosθ and a larger angle. String length L = 1.0 m.