Gravity

What is the primary reason objects fall towards Earth when dropped?

• Because Earth has a magnetic field that attracts objects.

• Because of a force called gravity that pulls objects towards Earth.

• Because the atmosphere pushes objects downwards.

• Because of the rotation of the Earth.

Answer explanation

The primary reason objects fall towards Earth is due to gravity, a force that pulls them towards the planet. This force is much stronger than any effects from the atmosphere or Earth's rotation.

Which two factors did Isaac Newton identify as essential for calculating the gravitational pull between two objects?

• Volume and temperature

• Mass and distance

• Speed and direction

• Color and shape

Answer explanation

Isaac Newton identified mass and distance as essential factors for calculating gravitational pull. The gravitational force increases with greater mass and decreases with increased distance between the objects.

How does the mass of an object affect its gravitational pull?

• More massive objects exert a weaker gravitational pull.

• More massive objects exert a stronger gravitational pull.

• Mass does not affect gravitational pull.

• Only the distance affects gravitational pull.

Answer explanation

More massive objects exert a stronger gravitational pull due to the direct relationship between mass and gravity, as described by Newton's law of universal gravitation.

What happens to the gravitational pull between two objects as the distance between them increases?

• The gravitational pull increases.

• The gravitational pull decreases.

• The gravitational pull remains the same.

• The gravitational pull becomes zero.

Answer explanation

As the distance between two objects increases, the gravitational pull between them decreases. This is due to the inverse square law of gravitation, which states that gravitational force is inversely proportional to the square of the distance.

According to Einstein's general theory of relativity, how does mass affect space?

• Mass creates a magnetic field in space.

• Mass bends space.

• Mass has no effect on space.

• Mass flattens space.

Answer explanation

According to Einstein's general theory of relativity, mass causes the curvature of space around it. This bending of space is what we perceive as gravity, making 'Mass bends space' the correct choice.

Why do astronauts weigh less on the Moon than on Earth?

• Because the Moon has a stronger gravitational pull.

• Because the Moon is closer to the Sun.

• Because the Moon's surface gravity is weaker due to its smaller size.

• Because the Moon has no atmosphere.

Answer explanation

Astronauts weigh less on the Moon because its surface gravity is weaker due to its smaller size. The Moon's gravitational pull is about 1/6th that of Earth's, resulting in lower weight for objects and astronauts.

What role does gravity play in the movement of the Moon and Earth?

• Gravity causes the Moon to move away from Earth.

• Gravity keeps the Moon orbiting around Earth and Earth orbiting the Sun.

• Gravity has no effect on the Moon and Earth's movement.

• Gravity causes the Moon to rotate on its axis.

Answer explanation

Gravity is the force that keeps the Moon in orbit around Earth and also keeps Earth in orbit around the Sun. This gravitational interaction is essential for the stability of these celestial movements.

How does the analogy of a bowling ball on a trampoline help explain gravity?

• It shows how objects can float in space.

• It illustrates how massive objects bend space, causing smaller objects to move towards them.

• It demonstrates how objects can repel each other.

• It explains how objects can change color.

Answer explanation

The analogy of a bowling ball on a trampoline illustrates how massive objects, like the ball, bend the fabric of space, causing smaller objects to roll towards them, similar to how gravity pulls objects together.

What is the difference between mass and weight?

• Mass is the force exerted by gravity, while weight is the amount of matter in an object.

• Mass is the amount of matter in an object, while weight is the force exerted on an object's mass by gravity.

• Mass and weight are the same.

• Mass is measured in pounds, while weight is measured in kilograms.

Answer explanation

The correct choice states that mass is the amount of matter in an object, while weight is the force exerted on that mass by gravity. This distinction is crucial, as mass is constant, whereas weight varies with gravity.

What effect does the Moon's gravity have on Earth?

• It causes the Earth's rotation to speed up.

• It causes the Earth's tides.

• It has no effect on Earth.

• It causes the Earth's temperature to rise.

Answer explanation

The Moon's gravity primarily affects Earth by causing tides. The gravitational pull of the Moon creates bulges in the Earth's oceans, leading to the rise and fall of sea levels, which is known as tidal movement.