Gravitation Test

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Gravitation Test - 48

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Weekly Quiz Competition

Question 1
1 / -0

The __________ of an object does not change from place to place.

A
Weight

B
Velocity

C
Mass

D
Pressure

Solution

Mass is the amount of matter contained inside an object. Thus it does not change from place to the place. For example, the mass of an object will be $$5 \ kg$$ on earth as well as on moon but the weight of the object will differ.
Question 2
1 / -0

The weight of an object depends on

A
Mass of the object

B
Acceleration due to gravity acting on the object

C
Both A and B

D
None of the above

Solution

Weight is the force of attraction of the earth acting on a body.
Since $$F=m \times a$$
Acceleration can be replaced by acceleration due to gravity and force can be replaced by weight.
$$\therefore W = m\times g$$
Question 3
1 / -0

The force with which an object is attracted towards the earth is called its ____________.

A
Weight

B
Acceleration

C
Mass

D
Pressure

Solution

The weight of an object is the force with which it is attracted towards the earth.

So option A is the answer.
Question 4
1 / -0

A rectangular block is $$5\ cm\times 5\ cm\times 10\ cm$$ in size. The block is first immersed in water with $$5\ cm$$ side kept vertical. If it is then immersed with $$10\ cm$$ side kept vertical, what change will occur in the level in water?

A
No change

B
It will rise

C
It will fall

D
It may rise or fall depending on the density of block

Solution

The volume of the block is $$V=5\times 5\times 10 = 250\ cm^3$$
When the block is immersed in water,
$$\text {the volume of displaced water} = \text {volume of the block} (V)$$
No matter how the block is immersed, the volume of the block is not going to change.
Therefore, the level of water will not change if the block is immersed with the $$10\ cm$$ side kept vertical.
Question 5
1 / -0

Magnitude of buoyant force depends on __________.

A
Volume of liquid

B
Density of liquid

C
Weight of an object

D
Area of an object

Solution

$$\text{Buoyant force} = \text{Volume of the body immersed in the liquid}\times \text{ the density of the liquid}\times g$$

So the magnitude of the buoyant force depends on the density of the liquid as well as the Volume of the body immersed in the liquid.
Hence, option (B) is correct.
Question 6
1 / -0

Submarines, lactometers, hydrometers, etc. are designed according to __________.

A
Archimedes' principle

B
Bernoulli's principle

C
Principle of fluid flow

D
All of the above
Question 7
1 / -0

Weight of a body on the surface of earth = ______ if $$M = mass$$ of the body

A
$$M$$

B
$$Mg$$

C
$$M\times momentum$$

D
Zero

Solution

Weight of an object near the surface of earth is equal to the force of attraction by earth described by the product
$$= Mass\times acceleration$$ $$due$$ $$to$$ $$gravity$$
$$= M\times g$$
It is given by Newton Second law as $$F=ma$$ here $$a=g$$
so $$Weight=M\times g$$
Question 8
1 / -0

A particle is projected vertically upwards with velocity $$\displaystyle 40{ ms }^{ -1 }$$. Find the displacement and distance travelled by the particle in 6 s.
[take $$\displaystyle g =10 m/s^{2}$$]

A
$$60\ m, 100\ m$$

B
$$60\ m, 120\ m$$

C
$$40\ m, 100\ m$$

D
$$40\ m, 80\ m$$
Solution
Initial upward velocity $$u = 40$$ $$ms^{-1}$$
Let after time $$t$$, the particle reaches the maximum height.
So final velocity $$v=0$$
Acceleration $$a=-g$$
Using $$v = u - gt$$
$$\therefore$$ $$0 = 40 - 10 t$$ $$\implies t =4 $$ $$s$$
Thus after $$4$$ $$s$$, the particle starts the downward motion for another $$2$$ $$s$$
Distance traveled in upward motion:
Here we take $$a=-g$$ as it is downward (negative) and distance is upwards (positive)
$$S_1 = ut - \dfrac{1}{2}gt^2$$ where $$t = 4$$ $$s$$
$$\therefore$$ $$S_1 = 40 \times 4 - \dfrac{1}{2}10 \times 4^2 = 80$$ $$m$$
Distance traveled in downward motion
Here we take $$a=g$$ as it is downward (positive) and distance is also (positive)
$$S_2 = u't + \dfrac{1}{2}gt^2$$ where $$t = 2$$ $$s$$ and $$u' = 0$$
$$\therefore$$ $$S_2 = 0 + \dfrac{1}{2}10 \times 2^2 = 20$$ $$m$$
Total distance covered in $$6\ s$$: $$S_T = 80 + 20 = 100 $$ $$m$$
Displacement in $$6$$ $$ s$$:
$$S = ut - \dfrac{1}{2}gt^2$$ where $$t = 6$$ $$s$$
$$S = 40 \times 6 - \dfrac{1}{2}10 \times 6^2 = 60$$ $$m$$

Option A is the answer.
Question 9
1 / -0

A body is thrown vertically upward from a point 'A' $$125 \ m$$ above the ground. It goes up to a maximum height of $$250\ m$$ above the ground and passes through 'A' on its downward journey . The velocity of the body when it is at a height of $$70\ m$$ above the ground is: ($$\displaystyle g=10\ { ms }^{ -2 }$$)

A
$$\displaystyle 60\ { ms }^{ -1 }$$

B
$$\displaystyle 80\ { ms }^{ -1 }$$

C
$$\displaystyle 20\ { ms }^{ -1 }$$

D
$$\displaystyle 50\ { ms }^{ -1 }$$

Solution

At the maximum height, the velocity of the body is zero and then it starts falling down due to the action of gravity with an acceleration $$g = 10 \space m/s^2$$.
We will consider the motion of body from maximum height of $$250\ m$$ to the height $$70\ m$$ as a free fall.
Then, $$initial \space velocity \space (u)=0, \quad displacement \space (h)=250-70 =180 m, \quad acceleration \space (g)= 10 m/s^2$$
Using the equation of motion:
$$v^2-u^2=2gh$$
$$\Rightarrow v^2-0^2=2\times 10\times 180$$
$$\Rightarrow v^2 = 3600$$
$$\Rightarrow v=\pm 60\ m/s$$
Since the downward direction is taken as positive, $$v = 60 m/s$$ is the accepted result.
Question 10
1 / -0

Relative density is used by which of the following users

A
Geologists

B
Minerologists

C
Gemologists

D
All of the above

Solution

Relative density is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material (i.e., water). It is usually measured at room temperature (20 Celsius degrees) and standard atmosphere (101.325kPa). It is unitless.
Relative density is used by mineralogist and geologists for the determination of the mineral content of a rock or any other given sample. It is also used by gemologists as an aid in the identification of gemstones.
So, correct option is $$(D) \ All \ of \ the \ above$$

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Gravitation Test - 48

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Gravitation Test - 48

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SHARING IS CARING

Question 1

Weight

Velocity

Mass

Pressure

Solution

Question 2

Mass of the object

Acceleration due to gravity acting on the object

Both A and B

None of the above

Solution

Question 3

Weight

Acceleration

Mass

Pressure

Solution

Question 4

No change

It will rise

It will fall

It may rise or fall depending on the density of block

Solution

Question 5

Volume of liquid

Density of liquid

Weight of an object

Area of an object

Solution

Question 6

Archimedes' principle

Bernoulli's principle

Principle of fluid flow

All of the above

Question 7

$$M$$

$$Mg$$

$$M\times momentum$$

Zero

Solution

Question 8

$$60\ m, 100\ m$$

$$60\ m, 120\ m$$

$$40\ m, 100\ m$$

$$40\ m, 80\ m$$

Solution

Question 9

$$\displaystyle 60\ { ms }^{ -1 }$$

$$\displaystyle 80\ { ms }^{ -1 }$$

$$\displaystyle 20\ { ms }^{ -1 }$$

$$\displaystyle 50\ { ms }^{ -1 }$$

Solution

Question 10

Geologists

Minerologists

Gemologists

All of the above

Solution

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