1. Solution...
Click for answers

2. 01
A car goes around a curve of radius r at a constant speed v. Then it goes around a curve of radius 2r at speed 2v. What is the centripetal force on the car as it goes around the second curve, compared to the first?
(A) four times as big
(B) twice as big
(C) one-half as big
(D) one-fourth as big
Centripetal Force
Solution...

3. 02 Solution... Two objects attract each other gravitationally.
If the distance between their centers is cut in half,
the gravitational force
(A) is cut to one fourth.
(B) is cut in half.
(C) doubles.
(D) quadruples
Universal Gravitation
Solution...

4. 03
Two objects, with masses m1 and m2, are originally a distance r apart. The magnitude of the gravitational force between them
is F. The masses are changed to 2m1 and 2m2, and the distance
is changed to 4r.
What is the magnitude of the new gravitational force?
(A) F/16
(B) F/4
(C) 16F
(D) 4F
Universal Gravitation
Solution...

5. 04
A hypothetical planet has a mass of half that of the Earth and a radius of twice that of the Earth. What is the acceleration due to gravity on the planet in terms of g, the acceleration due to gravity at the Earth?
(A) g
(B) g/2
(C) g/4
(D) g/8
g in terms of G
Solution...

6. 05
Two planets have the same surface gravity, but planet B has twice the radius of planet A. If planet A has mass m, what is the mass of planet B?
(A) 0.707m
(B) m
(C) 1.41m
(D) 4m
g in terms of G
Solution...

7. 06
Satellite A has twice the mass of satellite B, and rotates in the same orbit. Compare the two satellite's speeds.
(A) The speed of B is twice the speed of A.
(B) The speed of B is half the speed of A.
(C) The speed of B is one-fourth the speed of A.
(D) The speed of B is equal to the speed of A.
Universal Gravitation
Centripetal Force
Solution...

8. 7
What is the gravitational force on a 70-kg person standing on the Earth, due to the Moon? The mass of the Moon is 7.36 × 1022 kg and the distance to the Moon is 3.82 × 108 m.
(A) 0.24 N
(B) N
(C) N
(D) N
Universal Gravitation
Solution...

9. 8
The mass of the Moon is 7.4 × 1022 kg and its mean radius is 1.75 × 103 km. What is the acceleration due to gravity at the surface of the Moon?
(A) 2.8 × 106 m/s2
(B) 9.80 m/s2
(C) 1.6 m/s2
(D) 0.80 m/s2
g in terms of G
Solution...

10. 9
An object weighs 432 N on the surface of the Earth. The Earth has radius r. If the object is raised to a height of 3r above the Earth's surface, what is its weight?
(A) 432 N
(B) 48 N
(C) 27 N
(D) 0 N
Universal Gravitation
Solution...

11. 10 Solution... The Earth has radius r. A satellite of mass 100 kg is
at a point 3r above the Earth's surface. What is the satellite's weight?
(A) 61 N
(B) 109 N
(C) 9000 N
(D) N
Universal Gravitation
Weight
Solution...

12. 11
A satellite is in a low circular orbit about the Earth (i.e., it just skims the surface of the Earth). What is the speed of the satellite? (The mean radius of the Earth is 6.38 × 106 m.)
(A) 5.9 km/s
(B) 6.9 km/s
(C) 7.9 km/s
(D) 8.9 km/s
Centripetal Force
Weight
Solution...

13. 12
The hydrogen atom consists of a proton of mass 1.67 × kg and an orbiting electron of mass 9.11 × kg. In one of its orbits, the electron is 5.3 × m from the proton. What is the mutual attractive force between the electron and proton?
(A) 1.8 x N
(B) 3.6 x N
(C) 5.4 x N
(D) 7.0 x N
Universal Gravitation
Solution...

14. 01
A car goes around a curve of radius r at a constant speed v. Then it goes around a curve of radius 2r at speed 2v. What is the centripetal force on the car as it goes around the second curve, compared to the first?
Centripetal Force

15. 02 Two objects attract each other gravitationally.
If the distance between their centers is cut in half,
the gravitational force
Universal Gravitation
The law of universal gravitation is an inverse square law.
If the distance between two objects is cut in half, the force
between them is reduced to one quarter.

16. 03
Two objects, with masses m1 and m2, are originally a distance r apart. The magnitude of the gravitational force between them
is F. The masses are changed to 2m1 and 2m2, and the distance
is changed to 4r.
What is the magnitude of the new gravitational force?
Universal Gravitation

17. 05
Two planets have the same surface gravity, but planet B has twice the radius of planet A. If planet A has mass m, what is the mass of planet B?
g in terms of G

18. on the satellite’s mass06
Satellite A has twice the mass of satellite B, and rotates in the same orbit. Compare the two satellite's speeds.
Centripetal Force
Universal Gravitation
Speed does not depend
on the satellite’s mass

19. 7
What is the gravitational force on a 70-kg person standing on the Earth, due to the Moon? The mass of the Moon is 7.36 × 1022 kg and the distance to the Moon is 3.82 × 108 m.
Universal Gravitation

20. 8
The mass of the Moon is 7.4 × 1022 kg and its mean radius is 1.75 × 103 km. What is the acceleration due to gravity at the surface of the Moon?
g in terms of G

21. 9
An object weighs 432 N on the surface of the Earth. The Earth has radius r. If the object is raised to a height of 3r above the Earth's surface, what is its weight?
Universal Gravitation
The law of universal gravitation is an inverse square law.
If the distance between two objects is increased by a factor
of three, the force is reduced by a factor of 9

22. 10 The Earth has radius r. A satellite of mass 100 kg is
at a point 3r above the Earth's surface. What is the satellite's weight?
Universal Gravitation
The law of universal gravitation is an inverse square law. If the distance between two objects is increased by a factor of three, the force is reduced by a factor of 9
Weight
The weight of the
satellite on Earth is
The weight of the
satellite 3r.

23. 11
A satellite is in a low circular orbit about the Earth (i.e., it just skims the surface of the Earth). What is the speed of the satellite? (The mean radius of the Earth is 6.38 × 106 m.)
Centripetal Force
Weight

24. 12
The hydrogen atom consists of a proton of mass 1.67 × kg and an orbiting electron of mass 9.11 × kg. In one of its orbits, the electron is 5.3 × m from the proton. What is the mutual attractive force between the electron and proton?
Universal Gravitation