Question

A grinding wheel (which is cylindrical) has radius 4.0 cm and a mass of 800 g.
a. Find the wheel’s moment of inertia.

b. What net torque must be applied to achieve an angular acceleration of 150 rad/s2?

c. With this acceleration, how many revolutions would the wheel make in getting up to a speed of 600 revolutions per minute?

Answer 1

One question at time:
a) http://upload.wikimedia.org/wikipedia/en/math/2/9/b/29bac02573ea5d0bbf08a7506e4e9b37.png
Use Iz, that is moment of inertia of circular disc

Answer 2

b) Torque = Inertia x angular acceleration

Answer 3

so a) = 0.000512 kgm^2

Answer 4

haven't calculated yet ... possibly. seems that you changed in SI

Answer 5

yes they like our answers in kg and m

Answer 6

for
c) \( (\omega_2)^2 = (\omega_1)^2 + 2 \alpha\theta\)
where omega2 is 600rev per min, omega2 = 0, alpha is angular accn.

find theta, and divide it by 2pi // that will be your answer.

Answer 7

I like in kg and m too.

Answer 8

b is .0768 Nm?

Answer 9

for c i got 190.985 revolutions

Answer 10

not really sure ... if your a) is correct then
b) must be 150/pi * 0.000512

Answer 11

b) must be 150/2pi * 0.000512

Answer 12

c) must be (600 *2pi/60)^2 = 2 * (150/2pi) theta

divide theta by 2pi, you will get rev.

Answer 13

b is .012223 then ?

Answer 14

I haven't calculated .. I am not quite sure about changing radian/sec like that in angular acceleration.

Answer 15

http://en.wikipedia.org/wiki/Radian_per_second

Answer 16

im getting a little over 13 revolutions. im not sure if that seems like a legitimate answer or not

Answer 17

you don't have answer at the back of your text??

Answer 18

no its questions that were written for us. Not in a text book

Answer 19

then best would be to search similar questions that have answers /// usually my answers are incorrect.

Answer 20

***numerical answers.