System of Particles and Rotational Motion Test

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System of Particles and Rotational Motion Test - 19

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Question 1
1 / -0

Which of the following has the maximum momentum?

A
A 100 kg vehicles moving at 0.02 ms$$^{-1}$$.

B
A 4 g weight moving at 10,000 cms$$^{-1}$$.

C
A 200 g weight moving with kinetic energy of 10$$^{-6}J$$.

D
A 20 g weight after falling one kilometer.

Solution

Momentum is defined as mass times velocity .
Calculating for every option in SI units gives maximum value for option D.
Question 2
1 / -0

When the velocity of a body is doubled

A
kinetic energy is doubled

B
acceleration is doubled.

C
momentum is doubled.

D
potential energy is doubled.

Solution

Momentum is directly proportional to the velocity, hence if velocity is doubled momentum will be doubled.
Question 3
1 / -0

State whether true or false :
The position of centre of gravity of a body remains unchanged even when the body is deformed.

A
True

B
False

C
Ambiguous

D
Data insufficient

Solution

Centre of gravity means a point on which the weight of a body or system may be considered to act. In uniform gravity it is the same as the centre of mass. For regular bodies it is same as centre of that particular body. But if we deform it, it might change the shape leading the change in centre of gravity or else it might become irregular body that might not be uniform. Hence centre of gravity's position changes. Hence given statement is false.
Question 4
1 / -0

A stick is thrown in the air and lands on the ground at some distance from the thrower. The centre of mass of the stick will move along a parabolic path

A
in all cases

B
only if the stick is uniform

C
only if the stick has linear motion but no rotational motion

D
only if the stick has a shape such that its centre of mass is located at some point on it and not outside it

Solution

The motion of centre of mass of the body depends only on external forces.
Thus COM of the stick will move along a parabolic path in all cases .
Question 5
1 / -0

If the resultant of all external forces is zero, then velocity of centre of mass will be

A
zero

B
constant

C
either $$(a)$$ or $$(b)$$

D
neither $$(a)$$ nor $$(b)$$

Solution

$$F_{external}= M a_{CM}$$ where M is the total mass.
Zero net external force implies that $$a_{CM}= 0$$
Thus $$V_{CM} = constant$$ OR zero
(If the system is at rest initially, then $$V_{CM}= 0$$)
Question 6
1 / -0

The motion of centre of mass depends on

A
total external forces

B
total internal forces

C
sum of $$(a)$$ and $$(b)$$

D
None of these

Solution

The motion of centre of mass depends only on the net external force.
Let M be the total mass.
$$\vec{F}_{external} = M\vec{a}_{CM}$$
Question 7
1 / -0

A bullet of mass $$A$$ and velocity $$B$$ is fired into a block of wood of mass $$C$$. If loss of any mass and friction be neglected, the velocity of the system must be

A
$$\displaystyle\frac{AB}{A + C}$$

B
$$\displaystyle\frac{A + C}{B + C}$$

C
$$\displaystyle\frac{AC}{B + C}$$

D
$$\displaystyle\frac{A + B}{AC}$$

Solution

initial momentum = AB
final momentum = v(A+C) (where V is the final velocity of the system)
$$v=\dfrac{AB}{A+C}$$
Question 8
1 / -0

A potter's wheel has ______ motion

A
rotatory

B
straight line

C
rectilinear

D
oscillatory

Solution

A potter's wheel exhibits only rotatory motion as the rim of the wheel rotates with certain angular acceleration about an axis passing through the center of the wheel.
Question 9
1 / -0

Centre of gravity of the circular ring will be:

A
At the periphery

B
At the center

C
Outside it

D
None

Solution

Centre of gravity of the circle lies at its geometric centre because the resultant weight of the circle acts at its centre.
Question 10
1 / -0

A spinning top has a ______ motion

A
rotatory

B
circulatory

C
linear

D
straight line

Solution

A spinning top has a rotatory motion because it spins (or rotates) with a certain angular acceleration about an axis passing through its center.

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Re-Attempt Weekly Quiz Competition

System of Particles and Rotational Motion Test - 19

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System of Particles and Rotational Motion Test - 19

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Question 1

A 100 kg vehicles moving at 0.02 ms$$^{-1}$$.

A 4 g weight moving at 10,000 cms$$^{-1}$$.

A 200 g weight moving with kinetic energy of 10$$^{-6}J$$.

A 20 g weight after falling one kilometer.

Solution

Question 2

kinetic energy is doubled

acceleration is doubled.

momentum is doubled.

potential energy is doubled.

Solution

Question 3

True

False

Ambiguous

Data insufficient

Solution

Question 4

in all cases

only if the stick is uniform

only if the stick has linear motion but no rotational motion

only if the stick has a shape such that its centre of mass is located at some point on it and not outside it

Solution

Question 5

zero

constant

either $$(a)$$ or $$(b)$$

neither $$(a)$$ nor $$(b)$$

Solution

Question 6

total external forces

total internal forces

sum of $$(a)$$ and $$(b)$$

None of these

Solution

Question 7

$$\displaystyle\frac{AB}{A + C}$$

$$\displaystyle\frac{A + C}{B + C}$$

$$\displaystyle\frac{AC}{B + C}$$

$$\displaystyle\frac{A + B}{AC}$$

Solution

Question 8

rotatory

straight line

rectilinear

oscillatory

Solution

Question 9

At the periphery

At the center

Outside it

None

Solution

Question 10

rotatory

circulatory

linear

straight line

Solution

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