College Physics
2nd Edition
ISBN: 9780134601823
Author: ETKINA, Eugenia, Planinšič, G. (gorazd), Van Heuvelen, Alan
Publisher: Pearson,
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Textbook Question
Chapter 7, Problem 20P
* BIO Bone break The tibia bone in the lower leg of an adult human will break if the compressive force on it exceeds about
N (we assume that the ankle is pushing up). Suppose that a student of mass 60 kg steps off a chair that is 0.40 m above the floor. If landing stiff-legged on the surface below, what minimum stopping distance does he need to avoid breaking his tibias? Indicate any assumptions you made in your answer to this question.
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Students have asked these similar questions
A student lets a toy car roll four times down a ramp that is 1 m long. Each time the student covers the surface of the ramp with a different
material. The student measures the time it takes the car to roll down the ramp and records the results in the table below.
Time to complete
Material
Ramp (s)
4
8
Y
5
Which of these would be the best conclusion based on the data in the table?
O Different surfaces affect how fast a toy car accelerates.
O Different toy cars travel at different speeds.
O Gravity has little effect on the speed of toy cars on different surfaces.
O Air resistance is the greatest factor in limiting the acceleration of different toy cars.
A factory needs to move packages from one level to another using a ramp. They want to choose a material that has a specific coefficient of friction with the packages that will be sliding down the ramp.
What problem could occur if the coefficient of friction were too high?
A.Packages would go too fast and could break at the end of the ramp.
B.Packages could slow down too quickly and stop before the end of the ramp.
C.Packages could break the ramp because gravity would increase.
D.Packages could bounce off the ramp because normal force would increase.
2. A 5.00-kg rock piece is released from rest at
the top of a 2.50-m-long ramp, reaching a speed
of 1.75 m/s at the bottom. The ramp is inclined at
an angle of 30°. Calculate the coefficient of
kinetic friction between the rock and the ramp.
*Do not forget to draw the FBD*
Kinematic
VxVox + axt
1
x=x0+ x² + x²
voxt
v² = x + 2a, (x-xo)
1
x-xo=(vox + v)t
Equations
Vy = voy + ant
1
y
= 3 + Payt + ayt²
=
v=vy + 2a, (y - Yo)
10 = 1/2 (voy + v₂ ) t
y - yo =
139
(Heat
Newton's Laws of Motion
ΣF = 0
(Newton's 1st Law)
2 F = ma
(Newton's 2nd Law)
fsmax = Msn fk = Men
2.50 m
30°
g = 9.8 m/s²
weight = mass x g
Chapter 7 Solutions
College Physics
Ch. 7 - Review Question 7.1 Assuming that Earths orbit...Ch. 7 - Review Question 7.2 A system can possess energy...Ch. 7 - Review Question 7.3 When we use the work-energy...Ch. 7 - Review Question 7.4 If the magnitude of the force...Ch. 7 - Review Question 7.5 Why, when friction cannot be...Ch. 7 - Review Question 7.6 What would change in the...Ch. 7 - Review Question 7.7 Imagine that a collision...Ch. 7 - Review Question 7.8 Toyota says that the power of...Ch. 7 - Review Question 7.9 In this section you read that...Ch. 7 - In which of the following is positive work done by...
Ch. 7 - 2. Which answer best represents the system’s...Ch. 7 - An Atwood machine is shown in Figure Q7.3. As the...Ch. 7 - Prob. 4MCQCh. 7 - 5. Three processes are described below. Choose one...Ch. 7 - 6. Choose which statement describes a process in...Ch. 7 - 7. Which example(s) below involve(s) zero physics...Ch. 7 - 8. Estimate the change in gravitational potential...Ch. 7 - What does it mean if object 1 does +10 J of work...Ch. 7 - You pull on a spring, which obeys Hookes law, in...Ch. 7 - The graph in Figure Q7.11 shows the time...Ch. 7 - 12. A 1400-kg car is traveling on a level road at...Ch. 7 - Prob. 13MCQCh. 7 - Two clay balls are moving toward each other. The...Ch. 7 - 15. Is energy a physical phenomenon, a model, or a...Ch. 7 - 16. Your friend thinks that the escape speed...Ch. 7 - Suggest how you can measure the following...Ch. 7 - How can satellites stay in orbit without any jet...Ch. 7 - Why does the Moon have no atmosphere, but Earth...Ch. 7 - What will happen to Earth if our Sun becomes a...Ch. 7 - 21. In the equation , the gravitational potential...Ch. 7 - 22. You push a small cart by exerting a constant...Ch. 7 - 1. Jay fills a wagon with sand (about 20 kg) and...Ch. 7 - 2. You have a 15-kg suitcase and (a) slowly lift...Ch. 7 - * You use a rope to slowly pull a sled and its...Ch. 7 - A rope attached to a truck pulls a 180-kg...Ch. 7 - 5. You lift a 25-kg child 0.80 m, slowly carry him...Ch. 7 - A truck runs into a pile of sand, moving 0.80 m as...Ch. 7 - 7. A 0.50-kg block is placed in a straight gutter...Ch. 7 - s up a smooth incline, which makes an angle with...Ch. 7 - 9. ** It is a windy day. You are moving a 20-kg...Ch. 7 - A 5.0-kg rabbit and a 12-kg Irish setter have the...Ch. 7 - Prob. 11PCh. 7 - * A pickup truck (2268 kg) and a compact car (1100...Ch. 7 - * When does the kinetic energy of a car change...Ch. 7 - * When exiting the highway, a 1100-kg car is...Ch. 7 - Prob. 15PCh. 7 - 16. * Flea jump flea pushes off a surface by...Ch. 7 - * Roller coaster ride A roller coaster car drops a...Ch. 7 - 18. * BIO EST Heart pumps blood The heart does...Ch. 7 - 19. * Wind energy Air circulates across Earth in...Ch. 7 - 20. * BIO Bone break The tibia bone in the lower...Ch. 7 - 21. * BIO EST Climbing Mt. Everest In 1953 Sir...Ch. 7 - 22. A door spring is difficult to stretch. (a)...Ch. 7 - * A moving car has 40,000 J of kinetic energy...Ch. 7 - 24. * The force required to stretch a slingshot by...Ch. 7 - Jim is driving a 2268-kg pickup truck at 20 m/s...Ch. 7 - 26. * A car skids 18 m on a level road while...Ch. 7 - s mass is m. An average friction force of...Ch. 7 - Prob. 28PCh. 7 - Prob. 29PCh. 7 - 30. In a popular new hockey game, the players use...Ch. 7 - 31. The top of a descending ski slope is 50 m...Ch. 7 - * If 20% of the gravitational potential energy...Ch. 7 - Prob. 33PCh. 7 - 34. A driver loses control of a car, drives off an...Ch. 7 - * You are pulling a box so it moves at increasing...Ch. 7 - s speed increases from zero to 4.0 m/s in a...Ch. 7 - 37. ** EST Hit by a hailstone A 0.030-kg hailstone...Ch. 7 - 38. * BIO Froghopper jump Froghoppers may be the...Ch. 7 - 39. * Bar chart Jeopardy 1 Describe in words and...Ch. 7 - * Bar chart Jeopardy 2 Describe in words and with...Ch. 7 - 41. * Equation Jeopardy 1 Construct a qualitative...Ch. 7 - * Equation Jeopardy 2 Construct a qualitative...Ch. 7 - Prob. 43PCh. 7 - 44. * Evaluation 2 Your friend provides a solution...Ch. 7 - 45. A crab climbs up a vertical rock with a...Ch. 7 - 46 * Work-energy bar charts for a person going...Ch. 7 - Prob. 47PCh. 7 - * A 1060-kg car moving west at 16 m/s collides...Ch. 7 - * You fire an 80-g arrow so that it is moving at...Ch. 7 - 50. * You fire a 50-g arrow that moves at an...Ch. 7 - * To confirm the results of Problem 7.50, you try...Ch. 7 - 52. * Somebody tells you that Figure P7.52 shows...Ch. 7 - 54. A roofing shingle elevator is lifting a...Ch. 7 - 55. (a) What is the power involved in lifting a...Ch. 7 - * A fire engine must lift 30 kg of water a...Ch. 7 - * BIO Internal energy change while biking You set...Ch. 7 - * Climbing Mt. Mitchell An 82-kg hiker climbs to...Ch. 7 - * BIO EST Sears stair climb The fastest time for...Ch. 7 - * BIO EST Exercising so you can eat ice cream You...Ch. 7 - 61. ** BIO Salmon move upstream In the past,...Ch. 7 - * EST Estimate the maximum horsepower of the...Ch. 7 - Prob. 63PCh. 7 - At what distance from Earth is the gravitational...Ch. 7 -
65. * Possible escape of different air molecule...Ch. 7 - Determine the escape speed for a rocket to leave...Ch. 7 - Determine the escape speed for an object to leave...Ch. 7 - If the Sun were to become a black hole, how much...Ch. 7 - * A satellite moves in elliptical orbit around...Ch. 7 - 70. * Determine the maximum radius Earth's Moon...Ch. 7 - 71. You throw a clay ball vertically upward. The...Ch. 7 - Prob. 72GPCh. 7 - Prob. 73GPCh. 7 - 74 * EST A “gravity force car” is powered by the...Ch. 7 - * Loop the loop You are given a loop raceway for...Ch. 7 - 76. ** Atwood machine Two blocks of masses hang...Ch. 7 - andm2 are connected with a string that passes over...Ch. 7 - of all species became extinct, ending the reign of...Ch. 7 - s cradle is a toy that consists of several metal...Ch. 7 - 81. ** Six Flags roller coaster A loop-the-loop on...Ch. 7 - ** Designing a ride You are asked to help design a...Ch. 7 - BIO Metabolic rate Energy for our activities is...Ch. 7 - BIO Metabolic rate Energy for our activities is...Ch. 7 - BIO Metabolic rate Energy for our activities is...Ch. 7 - BIO Metabolic rate Energy for our activities is...Ch. 7 - BIO Metabolic rate Energy for our activities is...Ch. 7 -
BIO Kangaroo hopping Hopping is an efficient...Ch. 7 - BIO Kangaroo hopping Hopping is an efficient...Ch. 7 - BIO Kangaroo hopping Hopping is an efficient...Ch. 7 - BIO Kangaroo hopping Hopping is an efficient...Ch. 7 - BIO Kangaroo hopping Hopping is an efficient...Ch. 7 - BIO Kangaroo hopping Hopping is an efficient...
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