Ttorque angular acceleration units check

[mstram]

Given :

A (hypothetical) wheel with a m.o.i. of 1 lb*ft^2

Radius of wheel = 1.9099 inches, therefore circumference of wheel = 1 foot

The wheel is at rest, i.e. zero rotation speed.

A torque of 1 ft/lb is applied for 1 second

Is the result a rotation of 1 r.p.s. (60 r.p.m.) ?

thx
Mike

 

[jbriggs444]

Given :

A (hypothetical) wheel with a m.o.i. of 1 lb*ft^2

Radius of wheel = 1.9099 inches, therefore circumference of wheel = 1 foot

A torque of 1 ft/lb is applied for 1 second

Is the result a rotation of 1 r.p.s. (60 r.p.m.) ?

thx
Mike

If you are working in the system of U.S. customary units then you should carefully distinguish between pound-mass and pound-force. I see at least two problems with your result. Let's start with the easier one: What acceleration is produced when one pound force acts on one pound mass?

 

[mstram]

Sorry, I meant to write the initial rotation of the wheel is zero (at rest).

Does that make a difference ?

 

[jbriggs444]

Sorry, I meant to write the initial rotation of the wheel is zero (at rest).
Does that make a difference ?

It would make a difference. But It seemed clear that we were to assume a start from rest anyway.

Again, what acceleration would you expect from a one pound mass subject to a one pound force?