Question 1: Gravity is the force of attraction between two masses. In the context of the Solar System, gravity keeps planets orbiting the Sun. The strength of this force depends on the masses involved and the distance between them.

Answer: Gravity is the force of attraction between two masses, depending on their masses and the distance separating them.

Question 1: Define Newton's law of universal gravitation.

Answer: It states that every mass attracts every other mass with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.

Question 2: Explain why planets orbit the Sun rather than flying off into space.

Answer: Because of the gravitational force exerted by the Sun, which provides the centripetal force needed for planets to stay in orbit.

Question 1: Using Newton's law of universal gravitation, calculate the gravitational force between the Earth (mass = 5.97 × 10^24 kg) and the Moon (mass = 7.35 × 10^22 kg) separated by a distance of 384,400 km. (Use G = 6.674 × 10^-11 N·m^2/kg^2).

Answer: Approximately 1.98 × 10^20 N

Question 2: If the mass of a satellite is 1000 kg and it orbits Earth at a distance of 700 km above the surface (Earth's radius = 6371 km), what is the gravitational force acting on it? (G = 6.674 × 10^-11 N·m^2/kg^2).

Answer: Approximately 6,215 N

Question 1: Describe the key variables you would control in an experiment to measure the gravitational force between two objects.

Answer: Mass of the objects, distance between them, and environmental conditions such as air currents and vibrations.

Question 2: List two safety precautions that should be considered when conducting a theoretical experiment involving large masses and gravity.

Answer: Ensuring secure handling of heavy objects to prevent injury and maintaining a safe distance to avoid accidental collisions.

Question 1: A satellite orbits Earth at an altitude where the gravitational force is measured to be 5.3 × 10^3 N. If the satellite's mass is 1500 kg, what is the radius of its orbit from Earth's centre? (Earth's mass = 5.97 × 10^24 kg, G = 6.674 × 10^-11 N·m^2/kg^2, Earth's radius = 6371 km).

Answer: Approximately 7,200 km from Earth's centre

Question 2: Interpret the significance of the variation in gravitational force experienced by planets at different distances from the Sun.

Answer: The variation indicates that gravitational force decreases with increasing distance from the Sun, which explains why planets closer to the Sun have higher orbital velocities and shorter orbital periods, in accordance with Newton's law of universal gravitation.

Question 1: Explain how the concept of gravity is utilised in satellite navigation systems (GPS).

Answer: Gravity affects satellite orbits; understanding it allows precise calculations of satellite positions, ensuring accurate GPS signals for navigation.

Question 2: Describe one way in which knowledge of gravitational forces can aid in space exploration missions.

Answer: It helps in planning fuel requirements and trajectory calculations for spacecraft to efficiently reach other planets or celestial bodies.