Physics - Study Mode
[#366] Who defined the law of gravitation ?
Correct Answer
(A) Newton
Explanation
Solution: Isaac Newton put forward the law in 1687 and used it to explain the observed motions of the planets and their moons, which had been reduced to mathematical form by Johannes Kepler early in the 17th century.
[#367] It is difficult to fix a nail on a freely suspended wooden frame. Which law supports this statement?
Correct Answer
(C) Newton's third law
Explanation
Solution: Newton's third law supports this statement. When the wooden block is not resting against a support, the block and nails both move forward on being hit with a hammer. However, when the block is held firmly against a support, and the nail is hit, an equal reaction of the support drives the nail into the block.
[#368] In the Earth, the weight of a body is maximum at the
Correct Answer
(D) Surface
Explanation
Solution: Since weight of the body is directly proportional to g, the weight of the body is maximum at the centre of the earth and zero at the centre of the earth.
[#369] A person is hurt on kicking a stone due to
Correct Answer
(C) Reaction
Explanation
Solution: Newton’s third law states that “For every action, there is an equal and opposite reaction.” The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. So harder the stone is kicked, the harder will be its effect on the hitter.
[#370] The source of the Sun's energy is the process of
Correct Answer
(C) Nuclear fusion
Explanation
Solution: Solar energy is any type of energy generated by the sun. Solar energy is created by nuclear fusion that takes place in the sun. Fusion occurs when protons of hydrogen atoms violently collide in the sun's core and fuse to create a helium atom.