Question 1

A flywheel with mass 3kg and radius 30cm $(I=\frac{1}{2}mr^{2})$ initially at rest is brought to a angular velocity of 4 rad/s. Calculate its rotational energy.

Accepted Answer

1.08J

Answer

1.18J

Answer

1.38J

Answer

1.28J

Question 2

A blur-ray disc has, radius 15cm and a mass of 20g find the moment of inertia

(Moment of Inertia for a disc = $I=mr^{2})$

Accepted Answer

$4.5	imes10^{-4}kgm^{2}$

Answer

$5.5	imes10^{-4}kgm^{2}$

Answer

$7.5	imes10^{-4}kgm^{2}$

Answer

$6.5	imes10^{-4}kgm^{2}$

Question 3

The flywheel, which has a moment of inertia of $400 kgm^{2}$  is brought from rest to a angular velocity of 3000 rpm

Calculate the maximum kinetic energy which can be stored in the flywheel

Accepted Answer

$1.97	imes10^{7}$J

Answer

$4.97	imes10^{7}$J

Answer

$3.97	imes10^{7}$J

Answer

$2.97	imes10^{7}$J

Question 4

A constant force of 80 N is applied to the rim of the wheel which has a radius of 75 cm. The wheel has a moment of inertia of $2 kgm^{2}$.

Find the angular acceleration the wheel experiences.

Accepted Answer

30rad/$s^{2}$

Answer

20rad/$s^{2}$

Answer

10rad/$s^{2}$

Answer

40rad/$s^{2}$

Question 5

A wheel with mass 1.5kg and radius 50cm $(I=\frac{1}{2}mr^{2})$ initially at rest is brought to a angular velocity of 4 rad/s.

Calculate the gain in angular momentum

Accepted Answer

$0.75kgm^{2}s^{-1}$

Answer

$0.85kgm^{2}s^{-1}$

Answer

$0.95kgm^{2}s^{-1}$

Answer

$0.65kgm^{2}s^{-1}$

Question 6

A centrifuge  experiences a torque of 50Nm over a period of 5s.

What change in angular momentum does the centrifuge experience?

Accepted Answer

$250kgm^{2}s^{-1}$

Answer

$280kgm^{2}s^{-1}$

Answer

$220kgm^{2}s^{-1}$

Answer

$200kgm^{2}s^{-1}$

Question 7

While kicking a ball, a player rotates his leg about the hip joint.

The moment of inertia of the leg is $3.75 kgm^{2}$ and its rotational kinetic energy is 175 J.

What is the angular velocity of the leg

Accepted Answer

9.7 rad/s

Answer

7.7 rad/s

Answer

6.7 rad/s

Answer

8.7 rad/s

Related quizzes

Related quizzes