What is the correct relationship between the gravitational force and the distance between two point masses?
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Syllabus Edition
First teaching 2014
Last exams 2024
What is the correct relationship between the gravitational force and the distance between two point masses?
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The force, F between two point masses is 10 N. The distance, r between the two masses is doubled.
What is the new force between the two masses?
2.5 N
5 N
20 N
100 N
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The gravitational force, FG as shown on the diagram, keeps the Earth orbiting the Sun in a circular orbit.
What type of force is FG?
Electrostatic force
Centripetal force
Centrifugal force
Contact force
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Which expression best describes the relationship between the orbital time period, T and the orbital radius, r?
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Which of the following is not an equation which can be used to calculate g, the gravitational field strength?
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Which of the following statements about gravitational force is true?
Gravitational force has a finite range
A greater gravitational force is exerted on objects with larger mass
On planets with a large value of g, the gravitational force per unit mass is smaller than on planets with a smaller value of g
An object's mass changes depending on the gravitational field strength at that point
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An alien of mass 100 kg lives on a planet with a gravitational field strength of 50 N kg−1.
What is the weight of the alien on this planet?
5000 N
1000 N
0.05 N
100 N
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A commercial low-orbit space flight carries a passenger of mass 70 kg.
What is the approximate gravitational force of attraction between the Earth and the passenger?
0 N
7 N
700 N
7000 N
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A planet has twice the radius of the Earth and 4 times the mass. Assume the planet is spherical and of uniform density.
If the magnitude of the gravitational field strength on Earth is g, what is the magnitude of the gravitational field strength on the surface of the planet?
4g
8g
2g
g
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Which graph, plotted on logarithmic axes, shows Kepler's Third Law for the planets in our Solar System?
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The mass of a potential landing module heading for Jupiter is 4000 kg. The gravitational field strength on Jupiter is roughly 2.5 times that on Earth. What is the weight of the landing module on Earth?
4000 N
100 000 N
10 000 N
40 000 N
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A planet has triple the mass of Earth and a third of its radius. What is the gravitational field strength on the surface of the planet?
10 N kg-1
270 N kg-1
90 N kg-1
240 N kg-1
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The diagram below shows three uniform masses in a straight line.
The resultant gravitational force on the 1 kg mass is zero if the distance x is:
45 m
35 m
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The gravitational force between two identical uniform spheres of mass M is F when the distance between them d.
If the radius of each sphere is x, what is the correct expression for mass, M?
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A satellite of mass m is placed in a geostationary orbit. If the Earth’s angular velocity is ω rad s–1, what is the circumference of the satellite’s orbit?
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A spherical planet of uniform density has two times the mass of the Earth and three times the average radius. The magnitude of the gravitational field strength at the surface of the Earth is g. What is the gravitational field strength at the surface of the planet?
18g
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The inverse square law means that halving the radius of a planet results in quadrupling the gravitational field strength at its surface.
The centres of two planets are separated by a distance R. The gravitational force between the two planets is F. What will the force between the planets be when their separation increases to 4R?
4F
F
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A mass at point P gives rise to a gravitational field strength g at point X as shown.
An identical mass is placed at point Q as shown.
What is the resultant gravitational field strength at X in this new situation?
zero
between g and zero
between 2g and g
greater than 2g
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A spacecraft travels away from Earth in a straight line with its motors shut down. At one instant, the speed of the spacecraft is 5.7 km s-1. After a time of 1000 s, the speed is 5.2 km s-1. The gravitational field strength acting on the spacecraft during this time interval is:
–5 × 10–4 N kg–1
5 × 101 N kg–1
–5 × 10–1 N kg–1
–1 × 101 N kg–1
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Which of the following statements about uniform gravitational fields is incorrect?
The field strength is equal at every point in a uniform gravitational field
The acceleration of freefalling bodies is dependent on their mass
The field lines in a uniform gravitational field are parallel to each other
There is a uniform gravitational field near the Earth’s surface
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The weight of a body on the surface of a planet orbiting a star is 80 N. The star has twice the density of the planet and its diameter is 500 times greater.
What is the weight of the body on the surface of the star?
40 kN
80 kN
120 kN
160 kN
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Let r0 represent the radius of Earth.
Which of the following shows the variation of the magnitude of the Earth's gravitational field strength g with radial distance r from its centre of mass, r = 0?
You may assume that mass is uniformly distributed beneath the Earth's surface.
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At a point above a moon's surface and a distance from its centre, the gravitational field strength is 5 N kg–1. At the moon's surface itself, the field strength is 9 N kg–1.
Which of the following gives the value for the radius of the planet?
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A binary system consisting of a star of mass M and 5M orbit each other at a distance r between their centre of mass. The resultant gravitational field strength is zero along the line between their centres at a distance from the centre of the star of mass M. What is the value of the ratio ?
You may wish to use the quadratic formula:
For solutions to the equation:
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Which single condition enables Newton's universal law of gravitation to be used to predict the force between two masses m1 and m2?
m1 and m2 both have large radii
The radial distance between m1 and m2 is constant
m1 and m2 are very massive
m1 and m2 behave as point masses
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A planet of mass m and radius r rotates so rapidly that material at its equator only just remains on its surface. What is the period of its rotation?
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Two planetary systems, very far apart from each other, have suns with masses S1 and S2. They each have exoplanets P1 and P2 of mass m1 and m2 respectively, which are observed to have circular orbits of equal radii. If P1 completes an orbit in the time taken by P2, which of the following may be deduced?
S1 = S2 and m1 = 3m2
S1 = 3S2
S1 = 3S2 and m1 = m2
S1 = 9S2 only
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Two spherical bodies have the same radius, but one has thrice the mass of the other. At which point, A-D on the diagram below, could the resultant gravitational field of the two masses have the greatest magnitude?
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A mass m is placed at the centre of a thin, hollow, spherical shell of mass M and radius r.
What is the magnitude of the resultant gravitational force on m and M?
Magnitude of resultant gravitational force on m | Magnitude of resultant gravitational force on M | |
A. | 0 | |
B. | ||
C. | 0 | 0 |
D. | 0 |
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Two stationary bodies of mass m1 and m2 are a distance d apart. A third body, situated on the line joining m1 and m2, experiences no resultant gravitational force. Which of the following is a possible distance between the third body and m1?
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