Concept of Gravitation and Floatation
Physics concepts of gravitation, free fall, mass and weight, acceleration due to gravity, and the principles of floatation including buoyancy and relative density
Questions
Among the four bodies P, Q, R and S having masses 2 kg, 8 kg, 5 kg, 1 kg respectively, which one of these is pulled by the earth with the greatest force?
- P
- Q
- R
- S
- All bodies are pulled by the same force
The force exerted by a huge body like Earth, Moon, Sun, etc. on a smaller object near its surface is called
- gravity
- magnetic force
- electrostatic force
- mechanical force
- electromotive force
Choose the correct option
- When a body falls freely, its initial velocity is zero.
- When a body is thrown vertically upwards, its final velocity is zero.
- When a body is thrown vertically upwards, its final velocity is equal to initial velocity.
- Both (1) and (2).
- 1, 2 and 3 are correct.
What is the correct relation between pressure, thrust and area?
- Pressure = thrust × area
- Pressure = thrust/ area
- Pressure = thrust × (area)2
- Pressure = thrust/ (area)2
- Pressure = (area)2/ thrust
The mass of the earth is approximately
- 6 × 1022 kg
- 6 × 1023 kg
- 6 × 1024 kg
- 6 × 1020 kg
- 6 × 1021 kg
Choose the correct option:
- G is the acceleration due to gravity and g is the Universal Gravitation Constant
- G is the Universal Gravitation Constant and g is the acceleration due to gravity
- Both G and g are the acceleration due to gravity
- Both G and g are the Universal Gravitation Constant
- Both 1 and 2 are correct
A stone is dropped from a cliff. What will be its speed after falling 100 m?
- 9.8 m/s
- 44.2 m/s
- 19.6 m/s
- 98 m/s
- Zero
If the mass of one object is halved as compared to other objects, the force of attraction between them will be
- double the previous value
- half the previous value
- four times the previous value
- same as that of the earlier value
- one third of the earlier value
The force due to which a body keeps moving along the circular path is
- electrostatic force
- centripetal force
- gravitational force
- frictional force
- all of the above
The weight of an object of mass 10 kg on earth is __________.
- 10 N
- 1.02 N
- 98 N
- 98 kg
- 10 kg
The centripetal force is always acting
- towards the centre
- outwards
- tangentially
- both 2 and 3
- both 1 and 2
Which of the following physical quantities has no unit?
- Speed
- Density
- Relative density
- Volume
- Area
An instrument used to measure the relative density of a liquid is called
- hygrometer
- hydrometer
- barometer
- lactometer
- thermometer
A buoyant force of 100 g wt. acts on a body dipped completely in water. If the apparent weight of body is 50 g wt., then its actual weight is _______.
- 100 g wt
- 50g wt
- 150g wt
- 300 g wt.
- 250 g wt
If the distance between two planets is increased by a factor of 3, the gravitational force of attraction between them will be _________.
- increased by a factor of 3
- reduced by a factor of 3
- increased by a factor of 9
- reduced by a factor of 9
- independent of radius
The force of attraction between any two objects is called
- gravitational force
- frictional force
- electrostatic force
- magnetic force
- electromotive force
What is the mass of an object whose weight on earth is 392 N?
- 20 kg
- 9.8 kg
- 392 kg
- 4 kg
- 40 kg
If the weight of an object on the surface of the earth is 72N, its weight on the surface of the moon will be
- 36 N
- 432 N
- 6N
- 12N
- 18 N
The acceleration due to gravity is zero at __________.
- the equator
- poles
- sea levels
- the centre of the earth
- same at all places
At the centre of the earth
- mass of a body is zero, but weight is not zero.
- mass of a body is not zero, but weight is zero.
- both mass and weight of a body is zero.
- both mass and weight of a body is not zero.
- the value of g is 9.8.
According to the principle of flotation
- weight of the liquid displaced > weight of the floating body
- weight of the liquid displaced < weight of the floating body
- weight of the liquid displaced = weight of the floating body
- independance on the weight of the body
- liquids
Choose the correct option
- Mass is measured with a spring balance and weight is measured with a pan balance.
- Mass is measured with a pan balance and weight is measured with a spring balance.
- Both the mass and weight are measured with a spring balance.
- Both the mass and weight are measured with a pan balance.
- Both 1 and 2.
If acceleration due to gravity on earth is 10 m/s2 then, the acceleration due to gravity on moon is _________.
- 1.66 m/s2
- 16.6 m/s2
- 10 m/s2
- 0.166 m/s2
- 6.0 m/s2
A stone dropped from the roof of a building takes 2 seconds to reach the ground. What is the height of the building?
- 19.6 m
- 39.2 m
- 9.8 m
- 58.8 m
- 0
A boy from the roof of a building drops a stone. It takes 1s for the stone to reach the ground. The height of the building is [take g = 9.8 m/s2]
- 9.8 m
- 4.9 m
- 19.6 m
- 39.2 m
- 3.92 m