Here m = 8kg, g = 9.8so, F = 8 x 9.8 = 78.4 N

According to Newton all objects in the universe attract each other. This force of attraction between the objects is called gravitational force or gravity.

Both options, 1 and 2 are correct. So, the correct answer of this question is option 3

The thrust on unit area is called pressure. So,  option B is correct.

As we know that, F = GMm/ R2.
Where G = Gravitational constant, M = mass of the earth, m = mass of the another body at the surface of the earth, R = Radius of the earthor, F= ma ( here a = g) ma = GMm/ R2 Or M = g, R2/ GOr M = 9.8 (6.4×106)2 / 6.67 × 10 – 11 = 6× 1024 kg. It is the correct option

G is numerically equal to the force of attraction between two unit mass, placed at a unit distance. It is denoted by G, the acceleration produced in the motion of body under the effect of gravity is called acceleration due to gravity. It is denoted by g, so it is the correct option.

Yes, it is the correct answer. h = 100 m u = 0 v² = u² + 2gh = 0 + 2 x 9.8 x 100 v² = 1960 thus v = 44.2 m/s

As we know that F = GMm/R² F is proportional to m. So, if mass is half,  then force is also half  the earlier value. So,  it is correct

Centripetal force is an external force required to make a body move along circular path with uniform speed.

In uniform circular motion, acceleration is caused due to change in direction and is directed radially towards centre.

Relative density has no units.

Hydrometer is an instrument used to measure the relative density of a liquid.

Apparent weight of the object = Actual weight – buoyant force exerted. 50 = Actual weight -100 Actual weight =150 wt

The gravitational force between two bodies is given by F = GMm/R² If the distance between the two bodies R is increased by a factor of 3, the gravitational force F will reduce by a factor of 9.

According to Newton all objects in the universe attract each other. This force of attraction between the objects is called gravitational force or gravity. So it is correct.

Yes, it is the correct answer. W = mg 392 N = m x 9.8 m = 392/9.8 = 40 kg

As we know that weight depends on gravitational force acting on an object. On the surface of the moon, the value of acceleration due to gravity is one sixth compared to earth, so on the surface of moon the weight of the object is 1/6 x 72 = 12N.

The value of g does vary with altitude or height from the ground. The variation with height from the equation: g = GM/(R_E + h)²

Weight depends on acceleration due to gravity and its value varies from place to place . So, it may be zero.

According to the principle of flotation, weight of the liquid displaced is equal to the weight of the floating body.

Mass is the quantity of matter in a body regardless of its volume or of any forces acting on it. Mass is measured using a pan balance, a triple-beam balance, lever balance or electronic balance. While weight is a measurement of the gravitational force acting on an object. It is measured using a spring balance. So, it is incorrect

Gravity of Moon = 1/6 x gravity of Earth = (1/6) x 10 = 1.66 m/s²

Given: u = 0 t = 2 s h = ? We know that, h = ut + ½ gt² = 0 x 2+ ½ = ( 9.8 x 2 x 2)/2  = 19.6 m Thus, the height of the building =19.6 m

The motion of the body is under gravity. So here, u = 0, a = +g (as acceleration is in the direction of motion, i.e. 9.8 m/s²) t = 1 s Then, equation of motion is h = 1/2 gt² = 1/2  x  9.8 x 1 x 1 = 4.9 m