Gravity & weight

Figure 11 gives the values of gravitational field strength, g, on the surfaces of Earth, the Moon and Mars.

Calculate the ratio

A person has a weight of 730 N on Earth.

Calculate the person’s weight on the Moon, using information from Figure 11.

The gravitational field strength, g, is different on the surfaces of Earth, the Moon and Mars.

Explain why this is the case.

Asteroids have elliptical (oval) orbits around

*(c) Scientists have been searching beyond the Solar System to find planets where life could exist.

One requirement for life to exist on a planet is that there is water on the surface of the planet.

The planets where surface water could exist are in a region called the habitable zone.

Figure 12 is a diagram showing our Sun, with its five closest planets, and a more distant star with three of its planets labelled A, B and C. The habitable zone is shaded.

(Source adapted from: https://www.researchgate.net/publication/23993674_Darwin_-A_ Mission_to_Detect_and_Search_for_Life_on_Extrasolar_Planets/figures?lo=1)

Discuss the chance of life existing on the planets shown in Figure 12.

Your answer should refer to

• the five planets shown from our Solar System, giving the names of P, Q and R.

• the three planets, A, B and C, orbiting the more distant star.

Which row of the table shows the correct units of weight and of mass?

State the name of a piece of equipment that can be used to measure mass.

Figure 13 shows the two forces acting on a beach ball as it falls through the air.

The resultant of these two forces is 0.92 N downwards.

The mass of the beach ball is 0.25 kg.

Calculate the acceleration of the beach ball as it falls.

Use the equation

acceleration =_........ m / s²

Calculate the size of the air resistance force on the beach ball.

Some students are investigating forces.

They use a newton meter to keep a trolley stationary on a sloping runway, as shown in Figure 14.

They measure the force needed to keep the trolley stationary on the sloping runway.

They do this at four different places on the runway.

When the height, h, of the runway is 0.60 m, their four readings for force are

2.1 N 2.7 N 2.5 N 2.2 N

Calculate the mean value of these forces.

The students then measure values of the force, F, for several different values of h, the height of the runway.

Figure 15 is a graph of F against h.

Use the graph in Figure 15 to determine the value of F when h = 0.80 m.

Determine the gradient of the graph in Figure 15.

gradient =_........ N / m

Which of these is a scalar quantity?

A student has some cupcake cases.

One cupcake case is shown in Figure 14.

The student drops a stack of cupcake cases with the base facing downwards, as shown in Figure 15.

(Source: © Elena Schweitzer/Shutterstock)

Figure 15

The speed of the falling stack of cupcake cases depends on the number of cupcake cases in the stack.

The student also has a stop clock and a metre rule.

Describe an investigation to show how the speed of the falling stack of cupcake cases depends on the number of cupcake cases in the stack.

A stack of cupcake cases has a mass of 0.005 kg.

Calculate the weight, in newtons, of the stack of cupcake cases.

Gravitational field strength = 10 N / kg

Use the equation

W = mg

Figure 16 shows a cupcake case that is falling at a constant velocity.

Draw an arrow on Figure 16 to show the force due to air resistance on the cupcake case.

State the value of the acceleration of the cupcake case when it is falling at a constant velocity

A car travels along a straight road.

The car accelerates at 3 m / s² for a time of 7 s.

Calculate the change in velocity of the car.

Use the equation

change in velocity = acceleration × time taken

Which of these is a scalar quantity?

A student has some cupcake cases.

One cupcake case is shown in Figure 2.

The student drops a stack of cupcake cases with the base facing downwards, as shown in Figure 3.

(Source: © Elena Schweitzer/Shutterstock)

Figure 3

The speed of the falling stack of cupcake cases depends on the number of cupcake cases in the stack.

The student also has a stop clock and a metre rule.

Describe an investigation to show how the speed of the falling stack of cupcake cases depends on the number of cupcake cases in the stack.

A stack of cupcake cases has a mass of 0.005 kg.

Calculate the weight, in newtons, of the stack of cupcake cases.

Gravitational field strength = 10 N / kg

Use the equation

W = mg

Figure 4 shows a cupcake case that is falling at a constant velocity.

Draw an arrow on Figure 4 to show the force due to air resistance on the cupcake case.

State the value of the acceleration of the cupcake case when it is falling at a constant velocity.

Figure 5 shows a football kicked against a wall.

The football has a mass of 0.42 kg.

The football gains 11 J of gravitational potential energy as it moves from the ground to the wall.

Calculate the height at which the ball hits the wall.

Gravitational field strength = 10 N / kg

Use the equation

∆ GPE = m × g × ∆ h

Calculate the kinetic energy of the football when it is moving at a velocity of 12 m / s.

Use the equation

Describe the energy transfers that happen when the ball hits the wall.

A stone is held at rest above the ground.

The stone is released and falls until its velocity is 17 m / s.

Calculate the distance the stone has fallen when its velocity has reached 17 m / s.

A rock on the surface of the Earth has a mass of 12 kg.

Calculate the weight of this rock on the surface of the Earth.

The gravitational field strength on the surface of the Earth is 10 N/kg.

Use the equation

weight on the Earth =_........

The weight of the same rock on the surface of the Moon is 20 N.

Calculate the gravitational field strength on the surface of the Moon.

gravitational field strength on the Moon_........

*(b) Describe the Solar System in terms of the Sun, the planets, and the other objects which move in the Solar System.

Your answer should include the patterns of movement of the planets and the other objects in the Solar System.

You may draw a labelled diagram if it helps your answer.

The Sun is at the centre of our Solar System.

The planets orbit the Sun.

Which planet is nearest to the Sun?

The Moon orbits the Earth.

Which of these describes the Moon?

Any object weighs less on the Moon than it does on the Earth.

The gravitational field strength on the Moon is different from the gravitational field strength on the Earth.

Suggest two reasons why the gravitational field strength on the Moon is different from the gravitational field strength on the Earth.

The gravitational field strength on the Moon is 1.6 N/kg. The mass of a rock on the Moon is 6.0 kg.

Calculate the weight of this rock on the Moon.

State the unit of weight.

Use the equation

weight = mass gravitational field strength

Which of these planets is at the greatest distance from the Sun?

Use words from the box to complete the following sentences.

Saturn is a_........ .

The Moon is a_........ .

Halley’s Comet orbits a_........ .

Figure 3 shows a Mars Exploration Rover.

The mass of the rover is 190 kg.

The gravitational field strength on Earth is 10 N / kg.

Calculate the weight of the rover on Earth.

Use the equation

weight = mass × gravitational field strength

The weight of the rover on Mars is 700 N.

Calculate the gravitational field strength on Mars.

gravitational field strength on Mars =_........ N / kg

Which of these speeds would be normal for a person walking?

Figure 1 shows a block hanging from a spring balance.

Use a word from the box to complete the sentence below.

The quantity measured by the spring balance in Figure 1 is

A toy car has a mass of 0.10 kg. The toy car accelerates at 2.0 m/s².

Calculate the force producing this acceleration. State the unit.

Use the equation

F = m × a

Use words from the box to complete the sentences below.

Vectors have size and_........ .

Scalars have only_........ .

The symbol ‘ g ’ can be used to refer to the acceleration due to gravity.

The acceleration due to gravity ‘g’ has the unit of m/s².

‘ g ’ can also have another unit.

Which of these is also a unit for g ?

Two students try to determine a value for g, the acceleration due to gravity.

They measure the time, t, for a small steel ball to fall through a height, h, from rest.

They measure t to be 0.74 s, using a stopwatch.

They measure h to be 2.50 m, using a metre rule.

Calculate a value for g from the students’ measurements.

Use the equation

They record the time t for two more drops from the same height.

The three values for time t are

0.74 s, 0.69 s, 0.81 s.

Calculate the average value of time t to an appropriate number of significant figures.

Explain one way the students could improve their procedure to obtain a more accurate value for g.

A car travelling at 15 m/s comes to rest in a distance of 14 m when the brakes are applied.

Calculate the deceleration of the car. Use an equation selected from the list of equations at the end of this paper.