JEE Main 20 July 2021 Shift 2 Solved Paper

Given, initial angular speed,
ω0=600rpm=10rps
Final angular speed,
ωF=1800rpm=30rps
Time, t=10s
∵ We know that
ωF=ω0+αt
⇒‌‌30=10+α×10
⇒‌‌‌

30−10

10

=α
⇒‌‌α=‌

20

10

=2rps2
Angular displacement is calculated by the rotational equation of motion as
θ=ω0t+‌

1

2

αt2
where, θ is the angular displacement.
⇒θ=10×10+‌

1

2

×2×(10)2
⇒θ=100+100
⇒θ=200rad
Number of rotations
=‌

θ

2π

=‌

200

2π

=31.8≈32