Question

A wheel, originally rotating at 126 rad/s undergoes a constant angular deceleration of 5.00 rad/s2. What is its angular speed after it has turned through an angle of 628 radians?

Answer 1

Just like the linear kinematic equations
\[ \omega^2 = \omega_o^2 + 2 \alpha \theta\]
\[ \omega = \ \textrm{final angular velocity}
\\ \omega_o = \ \textrm{initial angular velocity}
\\ \alpha = \ \textrm{angular acceleration}
\\ \theta = \ \textrm{angular displacement}
\]

Answer 2

Yep I use that formula but I didnot get right answer

Answer 3

;/ What answer did you get?

Answer 4

http://www.google.com/url?q=http://sprott.physics.wisc.edu/phys103/exam2f01.pdf&sa=U&ei=Un5sUpeQFoPlyQHo7IHgAg&ved=0CBwQFjAB&usg=AFQjCNHjIj0QJ45f_q0lgoUcDfAp4PoRWA

that question exactly. 98 rad/s

Answer 5

\[ \alpha\] is negative ^_^

Answer 6

Why is that negative?

Answer 7

Acceleration is proportional to displacement
but acts in opposite direction to the displacement

Displacement is modeled by the sin graph,
differentiate that to get velocity = cos graph,
differentiate that to get acceleration = -sin graph

Answer 8

so they are always negative in any case right?

Answer 9

It's negative in this case because it's a "deceleration" - a negative acceleration.

The other way of saying it in this problem would be " an acceleration of -5.00 rad/s"

Answer 10

~~rad/s^2

Answer 11

The graph of the acceleration is always phase shifted by pi in relation to the angular displacement.

The magnitude of the acceleration is dependent on the problem.

Answer 12

thank so much I got it