# physics

posted by .

A compact disc (CD), initially at rest, reaches an angular speed of 40 rad/s in 5.0 s.
a. What is the magnitude of its angular acceleration?
b. How many revolutions does the CD make in 5.0 s?

• physics -

a. acceleration = speed / time ... 40 / 5.0

b. (average speed) * time
...[(0 + 40)/2] * 5.0

• physics -

## Similar Questions

1. ### college physics (inertia)

As a result of friction, the angular speed of a wheel changes with time according to dθ/dt = ω0 *e^-(σ*t) where ω0 and σ are constants. The angular speed changes from an initial angular speed of 3.08 rad/s …
2. ### college physics (inertia)

As a result of friction, the angular speed of a wheel changes with time according to dθ/dt = ω0 *e^-(σ*t) where ω0 and σ are constants. The angular speed changes from an initial angular speed of 3.08 rad/s …
3. ### college physics (inertia)

As a result of friction, the angular speed of a wheel changes with time according to dθ/dt = ω0 *e^-(σ*t) where ω0 and σ are constants. The angular speed changes from an initial angular speed of 3.08 rad/s …
4. ### physics

7.A turntable reaches an angular speed of 33.3 rpm, in 2.1 s, starting from rest. (a) Assuming the angular acceleration is constant, what is its magnitude?
5. ### physics

A discus thrower (with arm length of 1.2 m) starts from rest and begins to rotate counterclockwise with an angular acceleration of 3.0 rad/s2. (a) How long does it take the discus thrower's speed to get to 4.5 rad/s?
6. ### Physics

A discus thrower (with arm length of 1.2 m) starts from rest and begins to rotate counterclockwise with an angular acceleration of 3.6 rad/s2. (a) How long does it take the discus thrower's speed to get to 5.1 rad/s?
7. ### physics

A discus thrower (with arm length of 1.2 m) starts from rest and begins to rotate counterclockwise with an angular acceleration of 1.8 rad/s2. (a) How long does it take the discus thrower's speed to get to 3.4 rad/s?
8. ### physics

As a result of friction, the angular speed of a wheel changes with time according to d(theta)/dt = w0 e^-(aplpha*t) where w0 and alpha are constants. The angular speed changes from an initial angular speed of 4.87 rad/s to 4.27 rad/s …
9. ### physics

A disk rotates about its central axis starting from rest and accelerates with constant angular acceleration. At one time it is rotating at 7.8 rad/s; 60 radians later, its angular speed is 19 rad/s. Calculate (a) the angular acceleration …
10. ### Physics

An object initially rotating at an angular speed of 1.6 rad/sec turns through 30 revolutions during the time it experienced an angular acceleration of 0.32 rad/s^2. a) For how much time did the acceleration last?

More Similar Questions