- #1

- 28

- 0

This isn't really a homework problem, more of a "I'm-building-something-and-need-to-make-sure-the-physics-are-right-before-I-build-something-impractical" problem.

(I grouped it all together, easier for me to not separate each segment)

I need to spin a motor handle/crank at 25,000 rpm. I need to show that using a single flywheel attached to the spinning motor handle is unpractical.

I know that 25,000rpm is ~2618 rad/sec; this value should be angular frequency, ω, correct?

Then relating that to torque, tau = Iω, where I = mr^2 for a ring of radius r and mass m. And torque also equals tau = rFsinθ, where θ = 90°.

Therefore, Iω = rF

and F = mrω.

Assuming m = 1 kg, r = 0.5 m, F = ~1309 N

Therefore torque = ~655 Nm.

Are the physics relationships correct?

Thanks in advance.

EDIT: Also, tangential velocity is v = rω, correct?

## Homework Statement

## Homework Equations

## The Attempt at a Solution

(I grouped it all together, easier for me to not separate each segment)

I need to spin a motor handle/crank at 25,000 rpm. I need to show that using a single flywheel attached to the spinning motor handle is unpractical.

I know that 25,000rpm is ~2618 rad/sec; this value should be angular frequency, ω, correct?

Then relating that to torque, tau = Iω, where I = mr^2 for a ring of radius r and mass m. And torque also equals tau = rFsinθ, where θ = 90°.

Therefore, Iω = rF

and F = mrω.

Assuming m = 1 kg, r = 0.5 m, F = ~1309 N

Therefore torque = ~655 Nm.

Are the physics relationships correct?

Thanks in advance.

EDIT: Also, tangential velocity is v = rω, correct?

Last edited: