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The CD player rotates at 30 rev/min and takes 20s to reach this speed from rest. Calculate
(a) its angular acceleration, and
(b) the number of revolutions it makes before reaching its final speed


Sagot :

Answer:

The correct option is A

2

Explanation:

The correct option is A

2

π

30

rad s

2

Let us assume that the clockwise direction as positive,

it is given that the wheel is rotating with constant angular

velocity

ω

0

=

20

rev min

1

We know that,

=

1

rev/ min

=

1

60

rev/s

and we know that

1

complete revolution is

2

π

rad

, so

1

rev /min

=

2

π

60

rad/s

Hence

20

rev min

1

=

2

π

3

rad/s

.

It is given that the wheel comes to rest after

10

s

ω

=

0

is the final angular velocity, by the equation of motion

ω

=

ω

0

+

α

t

α

=

2

π

30

α

=

2

π

30

rad/s

2