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physics
conceptual physical science
Conceptual Integrated Science 2nd Edition Paul G Hewitt, Suzanne A Lyons - Solutions
A deer is a more concentrated form of energy than the grass it feeds on. Does this imply that the second law of thermodynamics is violated as the deer converts its food into tissue? Explain.
If you wish to warm 100 kg of water by 20°C for your bath, show that 8370 kJ of heat is required.
Why is it that you can safely hold your bare hand in a hot pizza oven for a few seconds, but, if you were to touch the metal inside, you’d burn yourself?
After boiling a bit of water in a gallon can and then sealing the can when water vapor has driven out most of the air, Dan Johnson and his class watch the can slowly crumple. Discuss the role of condensation of water vapor inside the can.What does the crumpling?
When scientists discuss kinetic energy per molecule, the concept being discussed is(a) temperature.(b) heat.(c) thermal energy.(d) entropy.
In a mixture of hydrogen gas, oxygen gas, and nitrogen gas, the molecules with the greatest average speed are those of(a) hydrogen.(b) oxygen.(c) nitrogen.(d) All have the same speed.
Your garage gets messier every day. In this case entropy is(a) decreasing.(b) increasing.(c) holding steady.(d) none of these
The specific heat capacity of aluminum is more than twice that of copper. If equal quantities of heat are added to equal masses of aluminum and copper, the metal that more rapidly increases in temperature is(a) aluminum.(b) copper.(c) Both increase at the same rate.(d) none of these
A bimetallic strip used in thermostats relies on the fact that different metals have different(a) specific heat capacities.(b) thermal energies at different temperatures.(c) rates of thermal expansion.(d) all of these
Water at 4°C will expand when it is(a) slightly cooled.(b) slightly warmed.(c) both cooled and warmed.(d) neither cooled nor warmed.
The principal reason one can walk barefoot on red-hot wood coals without burning the feet has to do with(a) the low temperature of the coals.(b) the low thermal conductivity of the coals.(c) mind-over-matter techniques.(d) none of these
Thermal convection is linked mostly to(a) radiant energy.(b) fluids.(c) insulators.(d) all of these
Which of these electromagnetic waves has the lowest frequency?(a) infrared(b) visible(c) ultraviolet(d) gamma rays
Compared with terrestrial radiation, the radiation from the Sun has(a) a longer wavelength.(b) a lower frequency.(c) both a longer wavelength and a lower frequency.(d) neither a longer wavelength nor a lower frequency.
What connection did Newton make between a falling apple and the Moon?
What does it mean to say that something moving in a curved path has a tangential velocity?
State Newton’s law of gravitation in words. Then state the law in one equation.
How does the brightness of light on a surface change when a point source of light is brought twice as far away?
Answer the preceding questions for the case of an elevator moving upward and then downward at constant velocity.
How much speed does a freely falling object gain during each second of fall?
With no gravity, a horizontally moving projectile follows a straight-line path. With gravity, how far below the straightline path does it fall compared with the distance of free fall?
What is the effect of air drag on the height and range of batted baseballs?
Why will a projectile that moves horizontally at 8 km/s follow a curve that matches the curvature of Earth?
Is it correct to say that the planets of the solar system are simply projectiles falling around the Sun?
In what location are the sense organs in humans that allow them to sense gravity?
Speculate on how the vestibular system might be involved in “space sickness”—the feeling of nausea and disorientation that astronauts experience.
Why does spreading feet apart help a surfer stay on the board?
What is the minimum speed for orbiting Earth in a close orbit? What is the maximum speed? What happens above this speed?
How was Pioneer 10 able to escape the solar system with an initial speed less than escape speed?
If you stood atop a super-tall ladder three times as far from Earth’s center as at Earth’s surface, how would your weight compare with it present value?
By what factor would your weight change if Earth’s diameter were doubled and its mass were doubled?
Calculate the force of gravity between Earth (6.4 х 1024 kg) and the Sun (2 x 1030 kg). The average distance between the two is 1.5 x 1011 m.
Students in a lab roll a steel ball off the edge of a table and measure its speed to be 4.0 m/s. They also know that if they simply dropped the ball from rest off the edge of the table it would take 0.5 s to hit the floor. How far from the bottom of the table should they place a small piece of
Is the force of gravity stronger on a piece of iron than it is on a piece of wood if both have the same mass? Defend your answer.
Is the force of gravity on a piece of paper stronger when it is crumpled? Defend your answer.
What are the magnitude and direction of the gravitational force that acts on a professor who weighs 1000 N at the surface of Earth?
Are the planets of the solar system simply projectiles falling around the Sun?
What path would you follow if you fell off a rotating merry-go-round? What force prevents you from following that path while you’re on the merry-go-round?
How does the vertical component of motion for a ball kicked off a high cliff compare with the motion of vertical free fall?
What would you say to a friend who says that, if gravity follows the inverse-square law, the effect of gravity on you when you are on the 20th floor of a building should be one-fourth as much as it would be if you were on the 10th floor?
The Moon falls toward Earth in the sense that it falls(a) with an acceleration of 10 m>s2, as do apples on Earth.(b) beneath the straight-line path it would follow without gravity.(c) both of these(d) neither of these
The force of gravity between two planets depends on their(a) planetary compositions.(b) planetary atmospheres.(c) rotational motions.(d) none of these
Inhabitants of the International Space Station do not have a(a) force of gravity on their bodies.(b) sufficient mass.(c) support force.(d) condition of free fall.
A spacecraft on its way from Earth to the Moon is pulled equally by Earth and the Moon when it is(a) closer to Earth’s surface.(b) closer to the Moon’s surface.(c) halfway from Earth to Moon.(d) at no point, since Earth always pulls more strongly.
If you tossed a baseball horizontally and with no gravity, it would continue in a straight line. With gravity it falls about(a) 1 m below that line.(b) 5 m below that line.(c) 10 m below that line.(d) none of these
When no air resistance acts on a projectile, its horizontal acceleration is(a) g.(b) at right angles to g.(c) centripetal.(d) zero.
Without air resistance, a ball tossed at an angle of 40°with the horizontal goes as far downrange as a ball tossed at the same speed at an angle of(a) 45°.(b) 50°.(c) 60°.(d) none of these
When you toss a projectile sideways, it curves as it falls. It will become an Earth satellite if the curve it makes(a) matches the curve of Earth’s surface.(b) results in a straight line.(c) spirals out indefinitely.(d) none of these
A satellite in elliptical orbit about Earth travels fastest when it moves(a) close to Earth.(b) far from Earth.(c) It travels at the same speed everywhere.(d) halfway between the near and far points from Earth.
A satellite in Earth’s orbit is mainly above Earth’s(a) atmosphere.(b) gravitational field.(c) both of these(d) neither of these
How can a huge ship have an enormous momentum when it moves relatively slowly?
How does impulse differ from force?
What are the two ways in which the impulse exerted on something can be increased?
For the same force, which cannon imparts the greater speed to a cannonball—a long cannon or a short one? Explain.
Consider a baseball that is caught and thrown at the same speed. Which case illustrates the greatest change in momentum—the baseball (a) being caught, (b) being thrown, or (c) being caught and then thrown back?
In the preceding question, which case requires the greatest impulse?
Can you produce a net impulse on an automobile by sitting inside and pushing on the dashboard? Defend your answer.
What does it mean to say that a quantity is conserved?
Distinguish between an elastic collision and an inelastic collision. For which type of collision is momentum conserved?
What do we call the quantity force х distance, and what quantity does it change?
In what units are work and energy measured?
True or false: One watt is the unit of power equivalent to 1 joule per second.
How many watts of power are expended when a force of 6 N moves a book 2 m in a time interval of 3 s?
Two cars, one twice as heavy as the other, are lifted to the same height in a service station. How do their potential energies compare?
When a car travels at 50 km/h, it has kinetic energy. How much more kinetic energy does it have at 100 km/h?
What is the evidence for saying whether or not work is done on an object?
The brakes do a certain amount of work to stop a car that is moving at a particular speed. How much work must the brakes do to stop a car that is moving four times as fast?
Cite the law of energy conservation.
Is it possible to design a machine that has an efficiency greater than 100%? Discuss.
How will the impulse differ if Cassy’s hand bounces back when striking the bricks?
The word burn is often used to describe the process of cellular respiration, in which cells release energy from the chemical bonds in food molecules. How is the “burning” that goes on in cells different from literal burning—for example, burning a log on a campfire?
In what sense are you powered by solar energy?
Place a small rubber ball on top of a basketball, and then drop them together. How high does the smaller ball bounce? Can you reconcile this with energy conservation?(What if the basketball was not elastic?)
Calculate the momentum of a 10-kg bowling ball rolling at 3 m/s.
Show that the momentum of a 50-kg carton that slides at 3 m/s across an icy surface is 150 kg•m/s.Impulse = Ft
Calculate the impulse that occurs when an average force of 10 N is exerted on a cart for 5 s.
Calculate the work done when a force of 2 N moves a book 3 m.
Show that 45 J of work is done when a 15-N force pushes a cart 3 m.Power = work done,time interval, p = W,t
Calculate the watts of power expended when a force of 1 N moves a book 2 m in a time interval of 1 s.
Show that 140 W of power is expended when a 20-N force pushes a cart 3.5 m in a time of 0.5 s.Gravitational potential energy = weight Χ height, PE = mgh
How many joules of potential energy does a 1.5-kg book gain when it is elevated 2 m? When it is elevated 4 m?(Let g = 10 N/kg.)
Show that there is a 600-J increase in potential energy when a 20-kg block of ice is lifted a vertical distance of 3 m.Kinetic energy: KE = 1/2 mv2
Calculate the number of joules of kinetic energy a 1-kg parrot has when it flies at 6 m/s.
Show that the kinetic energy of a 3-kg dog running at a speed of 4 m/s is 24 J.Work9energy theorem: Work = ΔKE, Fd = Δ1/2 mv2
How much work is required to increase the kinetic energy of a motor scooter by 4000 J?
Show that a 50-J change in kinetic energy occurs when a model airplane on takeoff is moved a distance of 5 m by a sustained net force of 10 N.
Consider the inelastic collision between the two freight cars in Figure 4.11. The momentum before and after the collision is the same. The kinetic energy, however, is less after the collision than before the collision. How much less, and what has become of this energy? U-10 U-5 FIGURE 4.11
Consider a car with a 25%-efficient engine that encounters an average retarding force of 500 N. Assume that the energy content of the gasoline is 40 MJ/L. Show that the car will get 20 km per liter of fuel.
When a cyclist expends 1000 W of power to deliver mechanical energy to her bicycle at a rate of 100 W, show that the efficiency of her body is 10%.
The decrease in PE for a freely falling object equals its gain in KE, in accord with the conservation of energy.(a) Using simple algebra, find an equation for an object’s speed v after falling a vertical distance h. Do this by equating KE to the object’s change in PE. (b) Then figure out how
What is the purpose of a “crumple zone” (which has been manufactured to collapse in a crash) in the front section of an automobile?
You’re on a small raft next to a dock, and you jump from the raft only to fall into the water. What physics principle did you fail to take into account?
A child can throw a baseball at 20 mph. Some professional ball players can throw a baseball at 100 mph, which is five times as fast. How much more energy does the pro ball player give to the faster ball?
Why is a punch more forceful with a bare fist than with a boxing glove?
A high-speed bus and an innocent bug have a headon collision. Is the sudden change in momentum of the bus greater than, less than, or the same as the change in momentum of the unfortunate bug? Discuss the distinction between momentum and a change in momentum.
A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is(a) zero.(b) doubled.(c) quadrupled.(d) unchanged.
When you are in the way of a fast-moving object and can’t escape, you will suffer a smaller force if the collision time is(a) long.(b) short.(c) The force is the same either way.
A 1-kg glider and a 2-kg glider slide toward each other at 1 m/s on an air track. They collide and stick. The combined gliders move at(a) 0 m/s.(b)½ m/s.(c) ⅓ m/s.(d) ⅔ m/s.
How much work is done on a 200-kg crate that is hoisted 2 m in a time of 4 s?(a) 400 J(b) 1000 J(c) 1600 J(d) 4000 J
When an increase in speed doubles the momentum of a moving body, its kinetic energy(a) increases, but less than doubles.(b) doubles.(c) more than doubles.(d) depends on factors not stated.
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