Final answer:
Gravity is the force that attracts objects towards the center of the Earth, causes ocean tides due to the Moon's gravitational pull, and keeps the planets in orbit around the sun, in accordance with Newton's law of universal gravitation.
Step-by-step explanation:
Gravity plays several critical roles in the universe and affects various natural phenomena. Gravity is the force that attracts objects toward the center of the Earth, which answers part a of the student's question. It is also responsible for the tides in the oceans due to the gravitational pull of the Moon and keeps the planets in orbit around the sun, as described in Newton's law of universal gravitation. This fundamental force, although the weakest among the four, has a vast influence on the structure and dynamics of the cosmos.
For the terms given in the descriptions:
- a. The force with which the Earth attracts a body is called gravitational force.
- b. The unit for energy is known as the joule.
- c. The movement of a body in the Earth's gravitational field when no other forces act on it is commonly referred to as free fall.
True Statements about Gravity:
- Earth does indeed exert a force due to gravity, and your body exerts the same force on the Earth; however, the effects are not as noticeable on Earth due to its much larger mass.
- The Moon and Earth exert forces that are equal in magnitude but opposite in direction on each other, resulting in the Moon's orbit around Earth.
- A rocket taking off does exert a force on the Earth, but since Earth's mass is significantly larger, this force does not have a noticeable effect on the planet.