Motion Under Gravity (Physics)

Total Questions: 41

1. Who among the following anticipated Newton by declaring that all the things gravitate to the earth. [I.A.S. (Pre) 1995]

Correct Answer: (d) Brahmagupta
Solution:

Brahmagupta was a great 7ᵗʰ century mathematician and astronomer. He was born in Bhinmal in Rajasthan. He is best known for his 'Brahmasphuta Siddhanta' in which he declared that all things gravitate to the earth.

2. Who gave the theory of gravity? [M.P.P.C.S. (Pre) 2010]

Correct Answer: (c) Issac Newton
Solution:

3. Who propounded the universal law of gravitation ? [M.P.P.C.S. (Pre) 2000, Uttarakhand U.D.A./L.D.A. (Pre) 2007]

Correct Answer: (a) Newton
Solution:

4. Astronauts in space can not stand erect. This is because in space - [U.P.P.C.S. (Mains) 2007]

Correct Answer: (a) There is a no gravity
Solution:

In space, astronauts can't stand erect because there is no gravity or microgravity. In this condition people or objects appear to be weightless. Microgravity affects the human body in several ways. For example muscles and bones can become weaker without gravity.

5. If an apple is released from an orbiting spaceship it will- [U.P.P.C.S. (Pre) 2010]

Correct Answer: (c) Move along with spaceship at the same speed
Solution:

If an apple is released from an orbiting spaceship, it will move along with the spaceship at the same speed.

6. The Leaning Tower of Pisa does not fall because- [U.P.P.C.S. (Pre) 2009]

Correct Answer: (d) The vertical line through the centre of gravity of the tower falls within its base
Solution:

Anything will remain stable as long as the vertical line through the centre of gravity falls within its base. The centre of gravity is that point where the whole mass of the body is supposed to be concentrated. Till today the vertical line from the centre of gravity has been falling within the base of this tower.

That is why it has not fallen. It is believed that when the tower leans further and the line from its centre of gravity passes out of its base, it will fall down.

7. If the distance between the Earth and the Sun were twice what it is now the gravitational force exerted on the earth by the sun would be - [U.P.P.C.S. (Mains) 2009]

Correct Answer: (c) One fourth of what it is now
Solution:

8. If an object is falling from the above, its weight remains- [M.P.P.C.S. (Pre) 1992]

Correct Answer: (b) Same
Solution:

In ideal conditions (when air resistance is negligible) if an object is falling from above, its weight remains same because mass of the object and the gravity remains unchanged.

9. If a feather, a rubber ball and a wooden ball are falling freely simultaneously from the same height in vacuum then : [67th B.P.S.C. (Pre) 2022]

Correct Answer: (d) All the three will reach at the ground together
Solution:

The feather, rubber ball and wooden ball will fall with the same speed and reach the ground together, because there is no air resistance in the vacuum, and gravitational force acts same on all the objects. Hence, every object undergoes free fall in the vacuum with the same acceleration.

10. If piece of equal size of woods, wax and iron falling from a same height, which one will reach the surface of the earth first? [R.A.S./R.T.S (Pre) 1992]

Correct Answer: (d) Reach at the same time
Solution:

In ideal conditions (when air resistance is negligible) all pieces of equal size of woods, wax and iron falling from same height despite their weight difference will hit the ground at the same time because the same gravitational acceleration (g) applies to all objects.