Gravitation quiz

The value of the universal gravitational constant G is:

The SI unit of pressure is:

The weight of an object on the Moon is about:

If the distance between two masses is doubled, the gravitational force becomes:

The acceleration due to gravity on Earth is about:

The mass of an object:

An object floats in water if its density is:

Thrust is:

The force that keeps the planets moving around the Sun is:

In a vacuum, a feather and a coin dropped together will:

Why does the Earth not move towards an apple though the apple attracts the Earth with an equal force? (2 marks)

What are tides? What causes them? (2 marks)

Why is the weight of an object less at the equator than at the poles? (2 marks)

Why do we feel lighter in water? (2 marks)

Why are the foundations of buildings made wide? (2 marks)

Why does a block of plastic released under water come up to the surface? (2 marks)

What is the importance of the universal law of gravitation? Give two phenomena it explains. (2 marks)

Why are railway tracks laid on sleepers? (2 marks)

Why does a stone thrown up come back down? (2 marks)

What happens to the gravitational force if the mass of both objects is doubled? (2 marks)

Find the gravitational force between two objects of 50 kg and 60 kg kept 2 m apart. (G = 6.67 x 10^-11 N m^2/kg^2.) (3 marks)

A ball is dropped from a height of 20 m. Find the velocity with which it hits the ground and the time taken. (Take g = 10 m/s^2.) (3 marks)

A body weighs 98 N on the Earth. Find its mass and its weight on the Moon. (Take g = 9.8 m/s^2.) (3 marks)

A force of 600 N acts on an area of 0.03 square m. Find the pressure. If the area is halved, what is the new pressure? (3 marks)

A ball is thrown up and reaches a maximum height of 80 m. Find its initial velocity and the time taken to reach the top. (Take g = 10 m/s^2.) (3 marks)

Read the passage and answer the questions. Astronauts on the International Space Station float inside it. The station orbits the Earth at a height of about 400 km, where the value of g is about 8.7 m/s^2. (i) Is there gravity at the height of the space station? (ii) Why do the astronauts appear to float? (iii) Does an astronaut's mass change in orbit? Explain. (5 marks)

Read the passage and answer the questions. A student weighs 500 N on Earth. She travels to the Moon, where g is about one-sixth of its value on Earth. (i) What is her mass? (Take g = 10 m/s^2.) (ii) What is her weight on the Moon? (iii) Why could she jump higher on the Moon? (5 marks)

Read the passage and answer the questions. A ship made of iron weighing thousands of tonnes floats in the sea, while a small iron nail sinks. (i) Why does the nail sink? (ii) Why does the ship float? (iii) Name the principle that explains this. (5 marks)

Read the passage and answer the questions. A woman wearing pointed heels finds them sinking into a soft lawn, while her friend wearing flat shoes walks easily. (i) Why do the pointed heels sink? (ii) Compare the pressure in the two cases. (iii) Give one more example from daily life of the same idea. (5 marks)

Read the passage and answer the questions. In a lab, a stone weighs 2 N in air and 1.5 N when fully immersed in water. (i) Find the buoyant force on the stone. (ii) What is the weight of water displaced by the stone? (iii) If immersed in salt water instead, would the reading be more or less than 1.5 N? Why? (5 marks)

State the universal law of gravitation and derive F = G m1 m2 / d^2 with a diagram. Explain why G is called a universal constant. (6 marks)

Derive the relation between g and G. Explain why g varies on the Earth's surface and decreases with height above the surface. (6 marks)

Draw a labelled diagram to show that pressure depends on area using a brick placed on sand on its different faces. Explain the observation. (6 marks)

Describe an experiment with a labelled diagram to verify Archimedes' principle. State two applications of the principle. (6 marks)

Draw velocity-time graphs for a ball thrown vertically up until it returns. Write the equations of motion for free fall and solve: a ball thrown up at 20 m/s, find maximum height and total time (g = 10 m/s^2). (6 marks)