Gravity: แบบฝึกหัด

What causes objects to fall towards the Earth?

Which of the following is a correct description of gravity as a force?

A person stands on a weighing scale inside an elevator. The diagram shows the elevator cable has broken, and the elevator is in a state of free-fall. What would the weighing scale read during the fall, and what is the scientific reason?

Which of the following correctly describes the relationship between the mass of an object and the gravitational force it experiences on Earth?

A student uses a spring balance to measure the weight of a 1 kg metal block on the Moon and then on the Earth. Which of the following statements about the measurements is correct?

Explain why objects fall towards the Earth, making reference to the concept of gravity.

An object has a mass of \(15 \text{ kg}\). If the gravitational field strength on a nearby asteroid is \(g = 0.5 \text{ N/kg}\), calculate the weight of the object on the asteroid and state the unit used for this measurement.

Astronauts in the International Space Station experience micro-gravity despite Earth's gravity still acting on them. Explain this phenomenon by describing the state of motion of the station and the astronauts relative to Earth.

An astronaut has a mass of 60 kg. He travels from the Earth to the Moon to conduct scientific experiments. On Earth, the gravitational field strength is approximately \( 10 \text{ N/kg} \). On the Moon, the gravitational field strength is only about \( 1.6 \text{ N/kg} \).

(a) State the main difference between mass and weight.
(b) Calculate the weight of the astronaut on the Earth.
(c) When the astronaut arrives on the Moon, what will be his mass and his weight? Show your calculations.

A ball is thrown vertically upwards with an initial velocity of \(25 \text{ m/s}\). Assume the acceleration due to gravity \(g = 10 \text{ m/s}^2\) downwards and neglect air resistance.

a) Calculate the time taken for the ball to reach its highest point.

b) Calculate the maximum height reached by the ball from the launch point.

c) What is the total time the ball remains in the air before it returns to its starting point?