Download Warm-up Problems

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Chapter 6
Section 6.1
Warm-up Problems
Warm-up problems for student textbook page 235
1. Determine the escape speed for a satellite that is near Earth that is attempting to leave the solar system. Assume that only
the mass of the sun is relevant, and that the mass of the rest of the solar system can be neglected.
2. Determine the escape energy of the Earth leaving the solar system.
3. Determine the escape speed and escape energy of a 355 kg space craft that has landed on Mars.
4. Determine the escape speed and escape energy of Pluto leaving the solar system.
Copyright © 2002 McGraw-Hill Ryerson Limited
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Chapter 6
Section 6.2
Warm-up Problems
Warm-up problems for student textbook page 246
1. A 125 kg satellite is in a circular orbit around the Earth with orbital radius 8.4  103 km. Determine the satellite’s
(a) gravitational potential energy.
(b) kinetic energy.
(c) speed.
(d) total energy.
(e) binding energy.
2. Repeat question 1 for a 235 kg satellite with orbital radius 9.2  103 km.
3. In question 1, suppose that the satellite loses 9.6  108 J of kinetic energy. As a result, the satellite drops down to a smaller
orbit. Assuming that the new orbit is circular, determine its radius.
4. A 115 kg satellite is in a circular orbit around the Earth at a speed of 15. 1 km/s. Determine the radius of its orbit.
Copyright © 2002 McGraw-Hill Ryerson Limited
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Chapter 6
Section 6.3
Warm-up Problems
Warm-up problems for student textbook page 255
1. Determine the thrust produced if 4.7  103 kg of gas exit the combustion chamber of a rocket per second, with a speed of
5.2 km/s.
2. Determine the thrust produced if 5.83  103 kg of gas exit the combustion chamber of a rocket per second, with a speed of
4.67 km/s.
3. If 8.2  103 kg of gas exit the combustion chamber of a rocket per second, and the thrust produced is 24.2 MN, at what
speed does the gas exit?
4. Determine the burn rate in kg/s if gas with an exhaust speed of 9.43 km/s exerts a thrust of 18.7 MN.
Copyright © 2002 McGraw-Hill Ryerson Limited
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Chapter 6
Chapter 6 Review
Warm-up Problems
Warm-up problems for student textbook pages 259–261
1. Determine the gravitational potential energy of a 120 kg object
(a) at Earth’s surface.
(b) 156 km above Earth’s surface.
2. A planet in another solar system has a mass twice Earth’s mass and its radius is twice Earth’s radius. How does its escape
speed compare with Earth’s escape speed?
3. An object of mass 2.5 kg is projected upward from the surface of the moon at an initial speed of 425 m/s.
(a) Determine the initial kinetic energy of the object.
(b) Determine the initial gravitational potential energy of the object.
(c) Determine the gravitational potential energy of the object when it reaches its peak height.
(d) Determine the object’s peak height.
4. A 78 kg astronaut is space walking 105 km above the surface of Earth.
(a) Determine the force that gravity exerts on the astronaut.
(b) Compare the result of part a with the astronaut’s weight on Earth’s surface.
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Unit 2 Review
Warm-up Problems
Warm-up problems for student textbook pages 264–269
1. A 1.4 kg object is moving with a speed of 14 km/h.
(a) Determine the momentum of the object.
(b) Determine the kinetic energy of the object.
2. A spring with spring constant 12 N/m is stretched by 7 cm.
(a) Determine the force stretching the spring.
(b) Determine the work done by the force in stretching the spring.
(c) Determine the elastic potential energy stored in the spring.
3. A 1450 kg car travelling at a velocity of 43 km/h East collides head on with a 1735 kg car travelling at a velocity of 38
km/h West. The cars stick together after the collision.
(a) Determine the momentum of each car before the collision.
(b) Determine the total momentum of the cars after the collision.
(c) Determine the speed of the cars after the collision.
(d) Determine the total kinetic energy of the cars before the collision.
(e) Determine the total kinetic energy of the cars after the collision.
(f) Explain why the results of parts d) and e) are different.
4. A 2.7 kg object is dropped from rest a distance of 27 km above the moon’s surface. Determine its speed just before it
strikes the surface of the moon.
Copyright © 2002 McGraw-Hill Ryerson Limited
Answers
Chapter 6
Section 6.1
Warm-up problems for student textbook page 235
1.
2.
3.
4.
4.2  104 m/s
5.3  1033 J
1.6  105 m/s, 4.5  1012 J
6.7  103 m/s, 2.8  1029 J
Section 6.2
Warm-up problems for student textbook page 246
1.
2.
3.
4.
(a) 5.9  109 J
(a) 1.0  1010 J
7.2  103 km
1.75  103 km
(b) 3.0  109 J
(b) 5.1  109 J
(c) 6.9 km/s
(c) 6.6 km/s
(d) 3.0  109 J (e) 3.0  109 J
(d) 5.1  109 J (e) 5.1  109 J
Section 6.3
Warm-up problems for student textbook page 255
1.
2.
3.
4.
2.4  107 N
2.7  107 N
3.0 km/s
1.98  103 kg/s
Chapter 6 Review
Warm-up problems for student textbook pages 259–261
1.
2.
3.
4.
(a) 7.5  109 J
(b) 7.3  109 J
same
(a) 2.3  105 J
(b) 7.1  106 J (c) 6.8  106 J
(a) 740 N
(b) 760 N
(d) 57 km
Unit 2 Review
Warm-up problems for student textbook pages 264–269
1.
2.
3.
4.
(a) 5.4 kg m/s
(b) 11 J
(a) 0.84 N (b) 0.03 J
(c) 0.03 J
(a) 1.7  104 kg m/s, 1.8  104 kg m/s (b) 990 kg m/s (c) 1.1 km/h
(d) 2.0  105 J
kinetic energy before the collision was converted to other forms of energy.
290 m/s
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(e) 155 J (f) Most of the