# Rotational Motion (NEET (NTA)-National Eligibility cum Entrance Test (Medical) Physics): Questions 7 - 12 of 125

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## Question number: 7

» Rotational Motion » Torque

MCQ▾

### Question

A child is standing with folded hands at the center of a platform rotating about its central axis. The kinetic energy of the system is K. The child now stretches his arms so that the moment of inertia of the system doubles. The kinetic energy of the system now is

(1) Less than 2K

(2) Equal to K/2

(3) More than K/4

(4) Equal to 4K

Select the correct answers and mark it according to the following codes:

### Choices

Choice (4) Response

a.

1,2 and 3 are correct

b.

2 and 4 are correct

c.

1 and 3 are correct

d.

1 and 2 are correct

## Question number: 8

» Rotational Motion » Torque

MCQ▾

### Question

A constant torque acting on a uniform circular wheel changes its angular momentum from Aq to 4Aq in 4 seconds. The magnitude of this torque is

### Choices

Choice (4) Response

a.

b.

c.

d.

## Passage

Consider a cylinder of mass M = 1kg and radius R = 1 m lying on a rough horizontal plane. It has a plank lying on its top as shown in the figure.

A force F = 55 N is applied on the plank such that the plank moves and causes the cylinder to roll. The plank always remains horizontal. There is no slipping at any point of contact.

## Question number: 9 (1 of 3 Based on Passage) Show Passage

» Rotational Motion » Angular Momentum

MCQ▾

### Question

Calculate the acceleration of cylinder.

### Choices

Choice (4) Response

a.

10 m/s 2

b.

5 m/s 2

c.

20 m/s 2

d.

Question does not provide sufficient data or is vague

## Question number: 10 (2 of 3 Based on Passage) Show Passage

» Rotational Motion » Angular Momentum

MCQ▾

### Question

Find the value of frictional force at A

### Choices

Choice (4) Response

a.

2.5 N

b.

7.5 N

c.

5.0 N

d.

None of the above

## Question number: 11 (3 of 3 Based on Passage) Show Passage

» Rotational Motion » Angular Momentum

MCQ▾

### Question

Find the value of frictional force at B

### Choices

Choice (4) Response

a.

5.0N

b.

2.5 N

c.

7.5 N

d.

None of the above

## Question number: 12

» Rotational Motion » Torque

MCQ▾

### Question

A constant torque of 700 N -m, turns a wheel of moment of inertia 50 kg -m 2 about an axis passing through the center. Angular velocity of the wheel after 2 s will be

### Choices

Choice (4) Response

a.