Kinematics of rotation Quiz 1

Question 1

An object is rotated such that its angular momentum is conserved around its centre. Discuss the motion of the object.

Accepted Answer

It moves in uniform circular motion

Answer

It moves in straight line

Answer

It moves in a haphazard manner

Answer

Inadequate Information

Question 2

A skater performs a trick whereby she runs horizontally off her practice board that is $$8.3\,m$$ above the ground, tuck herself into the “ball” mid-air and rotate her way down till she meets the ground.If the average angular speed of rotation is $$1.6\,rev/s$$ and the air resistance is negligible, determine how many revolutions she can make.

Accepted Answer

$$2.1\,revs$$

Answer

$$2.4\,revs$$

Answer

$$1.2\,revs$$

Answer

$$2\,revs$$

Question 3

A “T” shaped component of a machine is rotated keeping the longest side as an axis. Suppose the kinetic energy is $$K$$. The smaller lengths of the “T” shaped component are increased, such that the inertia doubles. What will be the new kinetic energy?

Accepted Answer

$$\dfrac{K}{2}$$

Answer

$$2K$$

Answer

$$\dfrac{K}{4}$$

Answer

$$4K$$

Question 4

A marble $$($$mass $$m$$ radius $$R)$$ is made to roll on a parabolic path named $$PQR$$ from a certain height $$H$$. Here part $$PQ$$ has high friction and $$QR$$ is smooth. If the maximum height that the marble will attain in part $$QR$$ is $$h$$ and $$R < < H$$. Then what is the ratio between $$\dfrac{h}{H}$$  $$ \ $$ <img  src="https://cmds-vedantu.s3.ap-southeast-1.amazonaws.com/prod/question-sets/d73bba46-2622-4524-84f2-d9c69e31d2782804036439753028697.png"/>

Accepted Answer

0.6

Answer

1

Answer

0.75

Answer

0.5

Question 5

Garima cuts a semi-circular disc of $$5\,g$$ with radius $$2\,cm$$ and rotates it by keeping the largest chord as the axis of rotation by applying a force of $$N$$ on an arbitrary point of the arc of the semicircle. If the region is said to be free from gravity, what will be the value of angular acceleration?

Accepted Answer

$$5\,rad/{{s}^{2}}$$

Answer

$$\dfrac{5}{2}\,rad/{{s}^{2}}$$

Answer

$$\dfrac{7}{5}\,rad/{{s}^{2}}$$

Answer

$$\dfrac{2}{5}\,rad/{{s}^{2}}$$