There is a girl pushing on a large stone sphere. The sphere has a mass of 8200 kgand a radius of 90 cm and floats with nearly zero friction on a thin layer of pressurized water. Suppose that she pushes on the sphere tangent to its surface with a steady force of F = 30N and that the pressured water provides a frictionless support. 1) How long will it take her to rotate the sphere one time, starting from rest?

Question

Physics

Robert Holder

11 November, 21:25

There is a girl pushing on a large stone sphere. The sphere has a mass of 8200 kgand a radius of 90 cm and floats with nearly zero friction on a thin layer of pressurized water. Suppose that she pushes on the sphere tangent to its surface with a steady force of F = 30N and that the pressured water provides a frictionless support. 1) How long will it take her to rotate the sphere one time, starting from rest?

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Answers (1)

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Adison Maynard · Answer 1

t = 35.16 s

Explanation:

Inertia

I = (2/5) * m*r²

I = (2/5) * 8200 kg * (0.9m) ²

I = 2657 kg·m²

τ = I*α

30N * 0.9m = 2657kg·m² * α

α = 0.01016 rad/s²

Θ = ½α*t²

2π rads = ½ * 0.01016rad/s² * t²

t = sqrt (4π rads/0.0106rad/s²)

t = 35.16 s