Question

Plz answer these questions

Answer 1

(1).
Rate of revolution = 3000/min = 3000/60s = 50/s
degree rotate in one revolution is 360°
In one seconds degree rotate is 50×360° = 18000°
(50 revolution in one second)

(2)
Rate of revolution of tire= 400/min=24000/h
car speed = 72 km/h

Car cover 72 km in one hour and No. of revolution of tire is 24000
No. of revolution × circumference = distance travelled
24000×circumference = 72 km
circumference = 72000m/24000 = 3m

Answer 2

Heya user,

(1) 3000 revolutions per minute means :->
----> ( 3000 / 60 ) revolutions per second
----> 50 rev / second... 
Now, 1 Revolution = 360° which means -->
-----> 50 revolutions per second goes :->
---------> 50 * 360° per sec = 18000° per sec

----> which means our motor's making 18000° rotation in one second....

(2) Well, 
---> Considering the Angular Velocity, Linear Velocity relation,
------> ωr = v
==> we have to find the Angular Velocity at 1st..

Now, ANGULAR VELOCITY is given by :->
---> 400 rev / min = 400 * 2π rad / 60 s ≈ 13.33 rad / s

Putting the value in given equation -->
---> r = v / ω = ( 72000 / 3600 ) / 13.33 = 20 / 13.33 ≈ 1.5 m
---> And hence, the radius of the tire is 1.5 m..

---> In case you're unknown of the term 'Angular Velocity' plz comment for an Alternative SOln..