Question

A wheel has a constant angular acceleration of a 4.2rad/s². during a certain time interval it turns through an angle of 140rad assuming that we started from rest . How long it had been motion before start of 8 seconds? (Ncert)

plz answer it step by step with explanation!!...​

Answer 1

Explanation:

Angular acceleration α=3rad/s

2

From rotational kinematics:

θ=ω1t+1/2αt 2[during the 4s internal]

60=4ω1+1/2×3×16

=4w1+24

4ω1 =36

ω1=9rad/s

The wheel starts from res, therefore ω0=0

ω1=ω0+αt′

9=0+3t′

t′=9/3 =3s