Answer: Option A. -> same in all directions
:
A
In a liquid, pressure acts in all directions equally. Due to this, pressure acts on both the horizontal walls of the container and its base.

Answer: Option A. -> 9.49×10−10 N
:
A
Given:
mass of first body $m_1=40kg$
mass of second body $m_2=80kg$
distance between two bodies, $R=15m$
$G=6.673\times {10}^{-11}N{m}^{2}k{g}^{-2}$
Acc. to Newton's law of gravitation, Gravitational force, $F=\frac{G{m}_1{m}_2}{R^2}$
So, $F=\frac{6.673\times {10}^{-11}\times 40\times 80}{{15}^2}$
On solving, we get $F=9.49\times {10}^{-10}N$

Answer: Option D. -> It is used in designing of laboratory thermometers.
:
D
Archimedes principle states that the upward buoyant force that is exerted on an object which is immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the object displaces.
It is used in the designing of ships, submarines. It is also used in lactometers and hydrometers as adulteration causes a change of density which can be easily identified using these tools. Archimedes principle has nothing to deal with the designing of thermometers.

Answer: Option D. -> weight decreases
:
D
The value of acceleration due to gravity is maximum at the surface of the earth. It decreases with increase in height from the surface. It also decreases with increase in depth from the surface. Hence, it is lower in the mine.

Since weight is the product of mass and acceleration due to gravity, it also decreases in a mine.

Answer: Option A. -> 49 N
:
A
Given, mass of a body $m=5kg$ and acceleration due to gravity $g=9.8m{s}^{-2}$.
As we know, weight,
$W=m\times g=5\times 9.8=49N$
Therefore, weight on the surface of the earth would be $49N$.

Answer: Option C. -> F∝1R2
:
C
According to the Universal law of gravitation, the gravitational force between twobodies is directly proportional to product of their masses and inversely proportional to the square of the distance between them. Thus, in this case, the gravitational force between the point masses isinversely proportional to $R^2$.
Hence, $F\propto \frac{1}{R^2}$

Answer: Option A. -> Pa and N
:
A
We know , Pressure $=\frac{Force}{Area}$
So,unit of pressure is$N{m}^{-2}$ which is called Pascal (Pa).
Sincethrust is the perpendicular force acting on a body, its unit is Newton (N).

Answer: Option B. -> False
:
B
Archimedes' principle states that the buoyant force exerted on a body submerged in a liquid is equal to the weight of the liquid displaced. Also, the force exerted on a body cannot be compared with a volume, as these are two different physical quantities.

Answer: Option A. -> 15 kgf
:
A
Combined weight of astronaut and his space suit on Earth $=60+30=90kgf$
Since, Moon's gravity is one-sixth of that ofthe Earth, the weight of the object on Moon is one-sixth of that on the Earth.
$\therefore$ the combined weight of the astronaut and his space suit on Moon is $\frac{90}{6}=15kgf$

Answer: Option D. -> All bodies in the universe
:
D
According to the law of gravitation, the force of gravitation between two bodiesis directly proportional to theirmasses and is inversely proportional to the square of the distance between them. Newton's law of gravitation is applicable to all the bodies in the universe. It remains valid everywhere in the universe.