Question 1: Define gravity and explain how it affects objects on Earth.

Answer: Gravity is a force of attraction between objects with mass. It causes objects to fall towards the Earth's surface and keeps planets in orbit around the Sun.

Question 2: Describe the mechanism by which gravity acts between two objects.

Answer: Gravity acts through a force of attraction that depends on the masses of the objects and the distance between them, as described by Newton's law of universal gravitation.

Question 3: Complete the sentence: The gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the __________ of the objects squared.

Answer: square distance

Question 4: What is the value of the acceleration due to gravity on Earth's surface? Provide the SI unit.

Answer: 9.8 m/s²

Question 5: Explain why astronauts in space experience microgravity even though Earth's gravity still acts on them.

Answer: Astronauts experience microgravity because they are in a continuous free-fall towards Earth, moving at a velocity that keeps them in orbit. This creates a sensation of weightlessness, even though gravity is still acting on them.

Question 1: Calculate the gravitational force between the Earth (mass = 5.97 × 10²⁴ kg) and the Moon (mass = 7.35 × 10²² kg) if the distance between them is 3.84 × 10⁸ metres. Use G = 6.67 × 10⁻¹¹ N·m²/kg².

Answer: Approximately 1.98 × 10²⁰ N

Question 2: If the mass of a satellite is 500 kg and it orbits at a distance of 7 × 10⁶ metres from Earth's centre, what is the gravitational force acting on it?

Answer: Approximately 4,576 N

Question 1: Design a simple experiment to demonstrate the effect of gravity on objects of different masses. List the variables involved and safety precautions to consider.

Answer: An experiment could involve dropping objects of different masses from the same height and measuring the time taken to reach the ground. Variables include mass (independent), height (controlled), and time (dependent). Safety precautions include ensuring objects are dropped in a clear area and using appropriate protective gear if necessary.

Question 1: A spacecraft orbits Earth at an altitude where the gravitational acceleration is 3.2 m/s². Explain how this relates to the Earth's surface gravity and what this means for objects in orbit.

Answer: The gravitational acceleration decreases with altitude. At this orbit, gravity is less than on Earth's surface (9.8 m/s²), causing objects to experience weightlessness and enabling satellites and spacecraft to orbit.

Question 2: Identify two industries or technologies that rely on understanding gravity and briefly describe how they benefit from this knowledge.

Answer: Aerospace industry uses gravity calculations for satellite deployment and space missions; civil engineering relies on gravity to design stable structures and foundations.