Question

A wheel is subjected to constant angular acceleration.at an instant its speed is 60 rad/s. After 10 seconds its speed is 80 rad/s. Then 10 sec before that instant,its speed was?

Answer 1

ans= 40 rad /sec

v = u + at

1. 60= u + at' .... at that instant

2. 80 = u + a(t' +10) ... after 10 sec

3. v = u + a(t'-10) .... before 10 sec of inst

substracting 1 and 2 we get a= 2.

so the constant angular acceleration is 2 rad /sec2

now...

substracting 2 and 3 we get

80- V = a( t' + 10 -t' + 10)

80 -V = 2(20)

80- V = 40

v = 40 rad /sec