Question

A wheel has a constant angular acceleration of 3.1 rad/s^2. During a certain 7.0 s interval, it turns through an angle of 140 rad. Assuming that the wheel started from rest, how long had it been in motion before the start of the 7.0 s interval?

Answer 1

tried doing this

Answer 2

1 eq: w^2 = wo ^2 +2a(theta)
2 eq: w-wo=at

but idk I just can't get it right

Answer 3

you're given,
\(\Delta \theta = 140\)
\(\Delta t =7 \)
\(\alpha = 3.1\)

try finding \(\omega_i\) using :
\[\Delta \theta = \omega_i \Delta t +\dfrac{1}{2}\alpha \Delta t^2 \]

Answer 4

once you have \(\omega_i\), you can find the time taken to reach that velocity

Answer 5

hi hmm okay wait

Answer 6

I got wi = 9.15

Answer 7

v=d/t ???

Answer 8

to get time?

Answer 9

or what

Answer 10

After getting wi(9.15) what equation will I use?

Answer 11

\(v=u+\alpha t\)

Answer 12

you know that the initial velocity is 0

Answer 13

\(\alpha =3.1\)

\(v = 9.15\)

Answer 14

\[9.15 = 0+3.1t\]

solve \(t\)

Answer 15

2.9516 thankyou