# A-level Physics Help Needed!!!

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#1
Can someone help me with question 3a ii)

A Rotor has a diameter of 4.5 m. It accelerates uniformly from rest to maximum angular velocity in 20 s. The total moment of inertia of the Rotor and the riders is 2.1 × 105 kg m2 .

(a) (i) At the maximum speed the centripetal acceleration is 29 m s–2 . Show that the maximum angular velocity of a rider is 3.6 rad s–1 .

i used the formula centripetal acceleration = angular speed squared x radius
and got the angular velocity as 3.59 rounded up to 3.6

(ii) Calculate the torque exerted on the Rotor so that it accelerates uniformly to its maximum angular velocity in 20 s. State the appropriate SI unit for torque.

I know torque is another word for moment but i dont know how to find it.
0
2 years ago
#2
Look at the formula sheet
http://filestore.aqa.org.uk/resource...A-7408-SDB.PDF
on the engineering physics section and find an equation that uses torque, time, inertia and angular velocity. Which equation have you found?
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#3
(Original post by ravioliyears)
Look at the formula sheet
http://filestore.aqa.org.uk/resource...A-7408-SDB.PDF
on the engineering physics section and find an equation that uses torque, time, inertia and angular velocity. Which equation have you found?
lol. im not doing engineering physics. i
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