Forces and Laws of Motion Test

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Forces and Laws of Motion Test - 53

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Weekly Quiz Competition

Question 1
1 / -0

A force of 2 N is applied on a particle for 2 sec, the change in momentum will be -

A
2 Ns

B
4 Ns

C
6 Ns

D
9 Ns

Solution
Question 2
1 / -0

A trolley of mass $$300 kg$$ carrying a sandbag of $$25 kg$$ is moving uniformly with a speed of $$27 km/h$$ on a frictionless track. After a while, sand starts leaking out of a hole on the trolley's floor at the rate of $$0.05 kg/s$$. The speed of the trolley after the entire sand bag is empty is

A
$$27 km /hr$$

B
$$9 km /hr$$

C
$$45 km /hr$$

D
$$54 km /hr$$

Solution
Question 3
1 / -0

A bullet of mass 25 g is fired from a rifle of mass 2 kg. Imagine that no other force are acting on the system. If the bullet travels with a velocity of 2 $${ ms }^{ -1 }$$ what will be the velocity of the recoil of the rifle ?

A
0.025 m/s

B
0.35 m/s

C
0.45 m/s

D
0.50 m/s

Solution

Given,
$$m_b=25g=0.025kg$$
$$m_r=2kg$$
$$v_b=2m/s$$
Applying conservation of linear momentum,
$$m_r\times v=m_b\times v_b$$
where v is the velocity of the recoil of the rifle
$$v=\dfrac{m_bv_b}{m_r}$$
$$v=\dfrac{0.025\times 2}{2}$$
$$v=0.025m/s$$
Question 4
1 / -0

A gun of weight of $$10 \,kg$$ fires a shot of $$0.5 \,g$$ with a velocity $$230 \,m/s$$. Velocity of recoil gun is-

A
$$1.51 \,cm/sec$$

B
$$1.15 \,cm/sec$$

C
$$1.5 \,cm/sec$$

D
$$1.10 \,cm/sec$$

Solution

Given,
$$m_g=10kg=10000g$$
$$m_b=0.5g$$
$$v_b=230m/s$$
The recoil velocity of gun is, $$V=\dfrac{m_bv_b}{m_g}$$
$$V=\dfrac{0.5\times 230}{10000}=1.15\times 10^{-2} m/s$$
$$V=1.15cm/s$$
The correct option is B.
Question 5
1 / -0

A simple pendulum hangs from the roof of a moving train. The string is inclined towards the rear of the train. What is the nature of the motion of the train?

A
Accelerated

B
Uniform

C
Retarded

D
None of above

Solution

The train is accelerated. This is why the ball hanging from the roof of the train inclines towards the rear of the train. The behavior of the ball is explained by the law of inertia.
The ball tries to be at rest when the train together with the rope is moving forward.
Hence option A is the correct answer.
Question 6
1 / -0

A gun fires a bullet of mass 50 g with a velocity of $$ 30 ms^{-1} $$. Because of this,the gun is pushed back with a velocity of $$ 1 ms^{-1} $$. The mass of the gun is.

A
5.5 kg

B
3.5 kg

C
1.5 kg

D
0.5 kg

Solution

Given,
$$m_b=50g$$
$$v_b=30m/s$$
$$v_g=1m/s$$
$$m_g=?$$
By the conservation of linear momentum,
$$Initial$$ $$momentum$$=$$Final$$ $$Momentum$$
$$0=m_bv_b-m_gv_g$$ minus sign because veloicity of gun is opposite to velocity of bullet.
$$m_bv_b=m_gv_g$$
$$\dfrac{50}{1000}\times 30=m_g\times 1$$
$$m_g=1.5 kg$$
The correct option is C.
Question 7
1 / -0

A gun recoils after firing to conserve:

A
velocity

B
momentum

C
force

D
speed

Solution

According to law of conservation of momentum, initial momentum is equal to the final momentum.
So, in order to conserve momentum, the gun recoils. Velocity, force and speed are not conserved.
Question 8
1 / -0

An athlete runs some distance before taking a long jump, because:

A
he gains energy to take him through the long distance

B
it helps to apply larger force

C
by running action and reaction forces increase.

D
by running he gives himself large inertia of motion.

Solution

An athlete runs before jumping to gain momentum because it helps in jumping higher and longer because of the inertia of motion gained due to motion. When the athletes jump, they already have a forward motion that would be greater than that of a jump made from standing in one spot. While running, the athlete cannot gain energy or apply larger force because initially, he would be rest and while running, he will lose energy.
Question 9
1 / -0

The momentum of a body of given mass is proportional to its:

A
speed

B
volume

C
density

D
shape

Solution

The property or tendency of a moving object to continue moving is called momentum. For an object moving in a line, the momentum is the mass of the object multiplied by its velocity. Volume, density, and shape does not determine the momentum.
Question 10
1 / -0

The acceleration of a body is to be doubled from its initial value. By what factor is the acting force to be increased ?

A
half

B
two

C
four

D
one

Solution

As we know,
$$Force \propto acceleration.$$
So, if acceleration is doubled, the force will also increase by a factor of two.

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Re-Attempt Weekly Quiz Competition

Forces and Laws of Motion Test - 53

Result

Forces and Laws of Motion Test - 53

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SHARING IS CARING

Question 1

2 Ns

4 Ns

6 Ns

9 Ns

Solution

Question 2

$$27 km /hr$$

$$9 km /hr$$

$$45 km /hr$$

$$54 km /hr$$

Solution

Question 3

0.025 m/s

0.35 m/s

0.45 m/s

0.50 m/s

Solution

Question 4

$$1.51 \,cm/sec$$

$$1.15 \,cm/sec$$

$$1.5 \,cm/sec$$

$$1.10 \,cm/sec$$

Solution

Question 5

Accelerated

Uniform

Retarded

None of above

Solution

Question 6

5.5 kg

3.5 kg

1.5 kg

0.5 kg

Solution

Question 7

velocity

momentum

force

speed

Solution

Question 8

he gains energy to take him through the long distance

it helps to apply larger force

by running action and reaction forces increase.

by running he gives himself large inertia of motion.

Solution

Question 9

speed

volume

density

shape

Solution

Question 10

half

two

four

one

Solution

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