Science Book Questions

Ch.3 p.52-56 #19: When an object is thrown upward, how much speed does it lose each second (ignoring air resistance)?

10 m/s for each second moving up

Ch.7 p.126-131 #21: What is the efficiency of machine that miraculously converts all the input energy to useful output energy?

100%

Ch.3 p.52-56 #21: What is the distance fallen for a freely falling object 1s after being dropped from a rest position? What is the distance for a 4s drop?

5m; 80m [4x4x5]

Ch.2 p.35-38 #9: What is the net force on a cart that is pulled to the right with 100 pounds of force and to the left with 30 pounds of force?

70 pounds to the right

Ch.5 p.85-89 #11: If the forces that act on a cannonball and the recoiling cannon from which it is fired are equal in magnitude, why do the cannonball and cannon have different accelerations?

The different accelerations are due to different masses.

Ch.3 p.52-56 #93: A friend says that if a car is traveling toward the east, it cannot at the same time accelerate toward the west. What is your response?

When the acceleration of a car is in a direction opposite to its velocity, the car is "decelerating," slowing down.

Ch.6 p.103-108 #43: When a supertanker is brought to a stop, its engines are typically cut off about 25km from port. Why is it so difficult to stop or turn a supertanker?

huge momentum

Ch.6 p.103-108 #9:Why is it advantageous to roll with the pouch in boxing?

increase time and decrease force

Ch.13 p.259-263 #1: How does pressure relate to force?

p = f/a

Ch.4 p.68-73 #1: Is acceleration proportional to net force, or does acceleration equal net force?

proportional

Ch.4 p.68-73 #91: When a parachutist opens her parachute after reaching terminal speed, in what direction does she accelerate?

up

Ch.3 p.52-56 #37: What is the instantaneous velocity of a freely falling object 10s after it is released from a position of rest? What is its average velocity during the 10s interval? How far will it fall during this time?

v = gt v = (-10m/s2)(10s) = -100m/s d = 1/2gt2 d = 1/2(-10m/s2)(100s2)= 500m

Ch.3 p.52-56 #17: What is the speed acquired by a freely falling object 5s after being dropped from a rest positions? What is the speed 6s after?

v = gt v = (-10m/s2)(5s) = 50m/s ; 60m/s

Ch.3 p.52-56 #35: You toss a ball straight up with an initial speed of 30 m/s. How high does it go, and how long is it in the air (ignoring fair resistance)?

v=gt 30m/s = -10m/s2(t) = 3s d = 1/2gt2 d= 1/2(-10m/s2)(9s2) = 45 m and 6s

Ch.7 p.126-131 #29: Show that 2.4J of work is done when a force of 2N moves a book 1.2m.

w=fd 2.4J = 2N(1.2m)

Ch.2 p.35-38 #21: A bowling ball at rest is in equilibrium. Is the ball in equilibrium when it moves at constant speed in straight-line path?

yes

Ch.3 p.52-56 #63: For a freely falling object dropped from rest, what is the acceleration at the end of the first second of fall? Tenth second of fall? Defend your answers.

10 m/s ?? constant g

Ch.2 p.35-38 #29: The sketch shows a painter's scaffold in mechanical equilibrium. The person in the middle weights 500N, and the tensions in each rope are 400N. What is the weight of the scaffold?

300N

Ch.2 p.35-38 #27: Lucy Light foot stands with one foot on one bathroom scale and her other foot on a second bathroom scale. Each scale reads 350N. What is Lucy's weight?

350N + 350N = 700N

Ch.13 p.259-263 #45: A merchant in Katmandu sells you a solid gold 1kg statue for a very reasonable price. When you get home, you wonder whether or not you got a bargain, so you lower the statue into a container of water and measure the volume of displaced water. Show that, for pure gold, the volume of water displace will be 51.8cm3.

Human density is about the same as water's, 1000kg/m3. From density = mV, we have V=m/density = (100kg)/(1000kg/m30 =.1m3

Ch.5 p.85-89 #71: A girl tosses a ball upward in Figure 5.27. If air drag is negligible, how does the horizontal component of velocity relate to Newton's first law of motion?

No horizontal forces, so the ball falls through the air in accord to the first law.

Ch.7 p.126-131 #3: Cite an example in which a force is exerted on an object without doing work on the object.

No work is done pushing on a wall.

Ch.4 p.68-73 #17: If we say that one quantity is directly proportional to each other, does this mean they are equal? Use weight and mass to explain.

No, weight proportional to mass but not equal

Ch.3 p.52-56 #71: If there were no air resistance, why would it be dangerous to go outdoors on a rainy day.

Rain would be falling super fast and it would hurt.

Ch.2 p.35-38 #47: If you're in a car at rest that gets hit from behind, you can suffer a serious neck injury called whiplash. What does whiplash have to do with Newton's first law?

Remains in rest due to the first law. There is a chair pushing your body forward but nothing on your head, so it is not pushed forward.

Ch.8 p.153-159 #5: What is rotational inertia, and how is it similar to inertia?

Rotational inertia is the resistance to change in a rotational motion and inertia is the resistance to change in velocity.

Ch.2 p.35-38 #53: What can you correctly say about a pair of vectors that add together to equal zero?

They are equal but opposite.

Ch.3 p.52-56 #87: Can you cite an example in which the acceleration of a body is opposite in direction to its velocity? If so, what example?

a car braking to a stop

Ch.2 p.35-38 #17: What does it mean to say something is in mechanical equilibrium?

add vertically to 0

Ch.3 p.52-56#29: Show that the average speed of a rabbit that runs a distance of 30 m in a time of 2s is 15 m/s.

av. speed: 30 m / 2s = 15 m/s

Ch.5 p.85-89 #5: Consider hitting a baseball with a bat. If we call the force on the bat against the ball the action force, identify the reaction force.

ball against the bat

Ch.8 p.153-159 #23: Is it inward or outward force that is exerted on clothes in a spin cycle of a washing machine?

clothes = inward

Ch.8 p.153-159 #91: You sit at the middle of a large turntable at an amusement park as it is set spinning and then allowed to spin freely. When you crawl toward the edge of the turntable, does the rate of the to ration increase, decrease, or remain unchanged? What principle supports this?

conservation of angular momentum: rotational inertia increases and angular speed decreases REMEMBER THIS

Ch.10 p.201-205 #3: A stone is thrown upward at an angle. What happens to the horizontal component of its velocity as it rises? As it falls?

constant

Ch.3 p.52-56 #53: Light travels in a straight line at a constant speed of 300,000 km/s. What is the acceleration of light?

constant acceleration = no acceleration so 0

Ch.3 p.52-56 #69: Consider a vertically launched projectile when air drag is negligible. When is the acceleration due to gravity greatest: when ascending, at the top, or when descending? Defend you answer.

constant g with no air drag

Ch.8 p.153-159 #1: What are the units of measurement for tangential speed? For rotational speed?

m/s r/min r/s

Ch.3 p.52-56 #39: Surprisingly, very few athletes can jump more than 2 feet straight up. Use d=1/2gt2 to solve for the time one spends moving upward in a .6m vertical jump. Then double it for the hang time - the time one's feet are off the ground.

d = 1/2gt2 = 5t2 t=.35 double that and get the hang time = .7s

Ch.3 p.52-56 #5: How far does a horse travel if it gallops at an average speed of 25 km/h for 30 min?

d = vt d = (25km/h)(.5h) = 12.5 km

Ch.10 p.201-205 #33: Calculate the hang time of a person who moves 3m horizontally during a 1.25m high jump. What is the hang time when the person moves 6m horizontally during this jump?

d =1/2gt2 3m=1/2(1om/s2)(t2) ??? ASK HOW TO DO THIS

Ch.8 p.153-159 #95: Strictly speaking, as more and more skyscrapers are built on the surface of Earth, does the day tend to become longer or shorter and does the falling f autumn leaves tend to lengthen or shorten the 24 hour day?What support this?

days longer with buildings opposite with leaves

Ch.4 p.68-73 #79: When blocking in football, a defending lineman often attempts to get his body under the body of his opponent and push upward. What effect does this have on the friction force between the opposing lineman's feet and the ground?

decreases

Ch.14 p.277-281 #13: By how much does the density of air increase when it is compressed to half its volume?

doubles

Ch.8 p.153-159 #7: As distance increases between most of the mass of an object and its center rotation, does rotational inertia increase or decrease?

increases with increasing distance

Ch.3 p.52-56 #3: What kind of speed is registered by an automobile speedometer: average speed or instantaneous speed?

instantaneous

Ch.14 p.277-281 #15: What is an ideal gas?

intermolecular forces the size of molecules that can be ignored

Ch.5 p.85-89 #51: If Mack truck and Honda Civic have a head-on collision, upon which vehicle is the impact force greater? Which vehicle experiences the greater declaration? Explain.

magnitude is equal, the bigger truck has less acceleration due to a greater mass

Ch.4 p.68-73 #9: Fill in the blanks: Shake something to and fro and you're measuring its .... Lift it against gravity and you're measuring its .....

mass, weight

Ch.8 p.153-159 #9: Which is easier to get swinging: a baseball bat held at the narrow end or closer to the massive end?

massive ASK ABOUT THIS

Ch.13 p.259-263 #71: Why will a block of iron float in mercury but sink in water?

mercury is more dense and can not displace the weight in the other

Ch.4 p.68-73 #5: Which is normally greater: static friction or sliding friction on the same object?

static

Ch.4 p.68-73 #13: In the string-pull illustration in Figure 4.8 a gradual pull of the lower string results in the top string breaking. Does this occur because of the ball's weight or its mass?

weight

Ch.13 p.259-263 #15: What is the condition in which the buoyant force on an object does equal the weight of the object?

when it is floating

Ch.9 p.177-181 #13: When is your weight measured as mg?

when you are firmly supported in equilibrium

Ch.7 p.126-131 #47: In raising a 5000N piano with a pulley system, the workers note that for every 2m of rope pulled onward, the piano rises .2m. Ideally, show that 500N is required to lift the piano.

workin = workout (Fx2m) = (5000Nx.2m) = 500N

Ch.6 p.103-108 #35: A 5kg fish swimming at 1m/s swallows an absentminded 1kg fish swimming toward it at a speed that brings both fish to a halt to immediately after lunch. Show that the speed of the approaching smaller fish before lunch must have been 5m/s.

(5kg)(1m/s) = (1kg)(velocity) 5m/s = velocity

Ch.3 p.52-56 #1: As you read this in your chair, how fast you moving relative the chair? Relative to the sun?

0, 30km/s

Ch.4 p.68-73 #25: What is the net force that acts on a 10N freely falling object?

10

Ch.9 p.177-181 #3: In what sense does the Moon "fall"?

It falls away from the straight line it would follow if there was no gravity. REMEMBER

Ch.10 p.201-205 #1: What exactly is a projectile?

Something that is projected bean some means and continues with its own inertia.

Ch.2 p.35-38 #55: A heavy bird sits on a clothesline. Will the tension in the clothesline be greater if the line sags a lot or if sags a little?

a little

Ch.3 p.52-56 #43: A ball is released at the left end of the three different tracks. The tracks are bent from equal - length pieces of channel iron. a. From fastest to slowest, rank the speeds of the balls at the right ends of the tracks. b. From longest to shortest, rank the tracks in terms of the times for the balls to reach the ends. c. From greatest to least, rank the tracks n terms of the average speeds of the balls. Or do al the balls have the same average speed on all three tracks?

a. B, A = C b. A, B, C c. C, B, A LOOK AT THIS

Ch.9 p.177-181 #107: If our Sun shrank in size to become a black hole, discuss and show front he gravitational force equation that Earth's orbit would not be effected.

(conservation) same mass and would continue to orbit

Ch.6 p.103-108 #19: Suppose a ball of putty moving horizontally with 1kgm/s of momentum collides with and sticks to identical ball of putty moving vertically with 1kgm/s of momentum. What is the magnitude of their combined momentum?

(resultant vector) sq. root 2kgm/s

Ch.13 p.259-263 #3: What is the relationship between liquid pressure n t the depth of a liquid? Between liquid pressure and weight density?

Liquid pressure is proportional to to depth and weight density.

Ch.2 p.35-38 #7: How does Newton's first law of motion relate to Galileo's concept of inertia?

Newton's first law of motion is ofter called the law of Inertia is just a restatement of Galieo's concept. It states that an object in rest will stay in rest unless acted on by another object and and object in motion will stay in motion unless acted on by another object.

Ch.3 p.52-56 #55: Yo are driving north on a high. Then without changing speed, you round a curve and drive east. a) does your velocity change? b) Do you accelerate? Explain.

Yes, change in direction and velocity.

Ch.5 p.85-89 #39: Consider a baseball player batting a ball. Identify the action-reaction pairs, (a) when the ball is being hit and (b) while the ball is in flight.

a) While the bat is in contact with the ball there are two interactions, one with the bat and Earth's gravity. Action: ball hits bat & Earth pulls down on ball Reaction: ball hits bat & ball pulls up on Earth. b) While the ball is in flight, again gravity and then air. Action: air pushes ball and Reaction: ball pushes air.

Ch.6 p.103-108 #37: Two automobiles, each of masses 1000kg, are moving at the same speed, 20 m/s, when they collide and stick together. In what direction and at why speed does the wreckage move (a) if one car was driving north and one south and (b) if one car was driving north and one east?

a) motionless b) 14 m/s, north east

Ch.2 p.35-38 #43: Asteroids have been moving through space for billions of years. What keep them moving?

nothing keeps them moving

Ch.2 p.35-38 #15: What is the net force on an object that is pulled with forces of 80 newtons to the right and 80 newton sot the left?

0

Ch.4 p.68-73 #87: What is the net force on a small 1N apple when you hold it at rest above your head? What is the net force on it after you release it?

0

Ch.3 p.52-56 #23: Consider these measurements: 10 m, 10 m/s, and 10 m/s2. Which is a measure of speed, distance, and acceleration?

10 m = distance 10 m/s = speed 10 m/s2 = acceleration

Ch.7 p.126-131 #77: On a playground slide, a child has potential energy that decreases by 1000J while her kinetic energy increases by 900J. What other form of energy is involved, and how much?

100J to thermal energy heating her and the slide.

Ch.2 p.35-38 #23: If you push a crate with a force of 100N and it slides at constant velocity, how great is the friction acting on the crate?

100N

Ch.3 p.52-56 #31: Show that the acceleration of a car that can go from rest to 100 km/h in 10s is 10km/hs.

100km/h / 10s = 10km/hs

Ch.10 p.201-205 #7: A projectile is launched upward at an angle of 70 degrees from the horizontal and strikes the ground a certain downrage. For what other angle would fall the same distance?

15 ASK ABOUT THIS

Ch.2 p.35-38 #19: Consider a book that weighs 15 N at rest on a flat table. How many newtons of support force does the table provide? What is the net force on the book in this case?

15 N; 0

Ch.10 p.201-205 #5: A projectile falls beneath the straight-line path it would follow if there were no gravity. How many meters does it fall below this line if it has been traveling for 1s? For 2s?

1s = 5m 2s =20m

Ch.9 p.177-181 #35: Calculate the force of gravity the Earth and the Moon exert on each other. The av. distance is 3.8x108.

2.1x10^20N

Ch.3 p.52-56 #33: Show that the hamster in the preceding problem travels a distance of 22.5m in 3s.

22.5m = 1/25m/s2(3s)

Ch.5 p.85-89 #25: Calculate the resultant of a horizontal vector with a magnitude of 4 units and a vertical vector with a magnitude of 3 units.

5 units

Ch.9 p.177-181 #5: What is the magnitude of the gravitational force between two 1kg bodies that are 1m part?

6x10^-11N

Ch.4 p.68-73 #47: A simple rearrangement of Newton's second law gives Fnet=ma. Show that a net force of 84N exerted on a 12kg package is need to produce an acceleration of 7.0m/s2.

84N= 12kg(a) 84N/12kg = 7m/s2 ? 12kg(7m/s2) = 84N

Ch.14 p.277-281 #17: Does the air exert a buoyant force on all objects in air or on only objects such as balloons that are very light for their size?

A buoyant force exists for all objects that displace fluids.

Ch.4 p.68-73 #29: Why does a heavy parachutist fall faster than a lighter one who wear a parachute of the same size?

A heavier parachutist must fall faster for air resistance to balance weight.

Ch.2 p.35-38 #41: What Aristotelian idea did Galileo demolish with his experiments with inclined planes?

Aristotle had said that objects need to be pushed to continue but Galileo they did not.

Ch.2 p.35-38 #37: Knowledge can be gained by philosophical logic and also by experimentation. which of these did Aristotle favor, and which did Galileo favor?

Aristotle: philosophical Galileo: experimentation

Ch.7 p.126-131 #19: If a machine multiplies force by a factor of 4, what other quantity is diminished, and by how much?

As the force increases, the distance decreases by the same factor.

Ch.9 p.177-181 #45: The planet and its moon gravitationally attract each other. Rank the forces of attraction between each pair, from greatest to least.

B = C, A, D

Ch.3 p.52-56 #95: Two balls are released simultaneously from rest at the left end of equal-length tracks A and B as shown. Which ball reaches the end of its track first?

B has a greater av. speed

Ch.2 p.35-38 #35: As seen from above, a stubborn stump is pulled by a pair of ropes, each with a force of 200N, but at different angles as shown. From greatest to least, rank the net forces on the stumps.

B, A, C

Ch.2 p.35-38 #89: Because Earth rotates once every 24 hours, the west wall in your room moves in a direction toward you at a linear speed that is probably more than 1000 km per hour. When you stand facing the wall, you are carried along at the same speed, so you don't notice it. But when you jump upward, which your feet no longer in contact with the floor, why doesn't the high-speed wall slam into you?

Because you are too moving the same speed.

Ch.2 p.35-38 #31: The weights of Burl, Paul, and the scaffold produce tensions in the supporting ropes. Rank the tensions in the left rope, from most to least, in the three situations. A, B, and C.

C, B, A

Ch.4 p.68-73 #55: In all three cases, A, B, and C, the crate is in equilibrium (no acceleration). Rank them by the amounts of friction between the carts and the floor, form greatest to least.

C, B, A

Ch.7 p.126-131 #121: To combat wasteful habits, we ofter speak of "conserving energy," by which we mean turning off lights and hot water when they are not being used and keeping thermostats at a moderate level. We also talk about "energy conservation." Distinguish the two.

Conserving energy = saving energy Energy conservation = law that states energy can not be created or destroyed

Ch.9 p.177-181 #33: Calculate the force of Earth's gravity on a 1kg mass at Earth's surface. The mass of Earth is 6x10^24kg and its radius is 6.4x10^6m. Does the result surprise you?

F = G m1m2/d^2 F=9.8N

Ch.4 p.68-73 #39: A small apple weighs about 1N. What is its mass in Kg? What is it's mass in lb?

F = ma 1N = m(10m/s) m = 1/10 kg (.1kg)(2.2lb/kg)= .22lb

Ch.4 p.68-73 #37: Calculate the weight in newtons of a 2oookg elephant.

F = ma F=2000kg(10m/s2) = 20000N

Ch.6 p.103-108 #31: A car carrying a 75kg test dummy crashes into a wall at 25m/s and is brought to rest in .1s. Show that the average force exerted by the seat belt on the dummy is 18,750N.

Ft=mv F = mv/t F = (75kg)(25m/s)/.1s = 18,750N

Ch.13 p.259-263 #77: Why is it inaccurate to say that heavy objects sink and light objects float? Examples.

Heavy object may or may not sink, deeding on their densities. Heavy actually means dense in this case. For example a ship doesn't just sink even though it is very heavy.

Ch.2 p.35-38 #5: What did Galileo discover about moving bodies and force in his experiments with inclined planes?

In the absence of friction, an object will continue to go in a straight line forever until it is stopped by another object.

Ch.6 p.103-108 #49: When you jump from a significant height, why is it advantageous to land with your knees slightly bent?

Increase the time and decrease the force

Ch.3 p.52-56 #15: What exactly is meant by a "freely falling" object?

It is only effected by gravity.

Ch.7 p.126-131 #69: A physics instructor demonstrates energy conservation by releasing a heavy pendulum bob, as shown in the sketch, and allowing it to swing to and fro. What would happen if, in his exuberance, he gave the bob a slight shove as it left his nose? Explain.

It will hit him in the face.

Ch.7 p.126-131 #37: Calculate the kinetic energy of an 84kg scooter moving at 10m/s.

Ke = 1/2mv2 Ke = 1/2(84kg)(10m/s) = 4200J

Ch.2 p.35-38 #49: Why do you seem to lurch forward in a bus that suddenly slows? Why do you seem to lurch backward when the bus picks up speed? What law applies here?

Law of Inertia

Ch.2 p.35-38 #85: Start a ball rolling down a bowling alley and you'll find that it moves slightly slower with time. Does this violate Newton's law of inertia? Discuss and defend your answer.

No, because the law is excluding friction. With air drag the ball will slow down.

Ch.3 p.52-56 #57: Starting from rest, one car accelerates to a speed of 50km/h and another 60km/h. Can you say which car underwent the greater acceleration? Why or why not?

No, because we do not know the time it took.

Ch.6 p.103-108 #67: If you throw a ball horizontally while standing on roller skates, you roll backward with a momentum that matches that of the ball. Will you roll backward if you go throughout the motions of throwing the ball but don't let go of it? Explain.

No, no momentum is given to the ball or you.

Ch.3 p.52-56 #91: If you drop an object, its acceleration toward the ground is 10 m/s2. If you throw it down instead, would its acceleration after throwing be greater than 10m/s2? Why or why not?

No, the acceleration is still 10m/s2.

Ch.1 p. 17 #1: What is science?

Science is the study of how things work and collecting information from it.

Ch.7 p.126-131 #59: Which requires more work: stretching a strong spring a certain distance or a weak one the same distance? Explain.

Stronger is more work for the same distance.

Ch.4 p.68-73 #85: A friend says that, as long as scar is at rest, no forces act on it. What do you say?

Support force and gravity ?? NO NET FORCE???

Ch.5 p.85-89 #1: When you push against a wall with your fingers, they bend because they experience a force. Identify this force.

The force is the wall pushing on your fingers.

Ch.5 p.85-89 #79: A farmer urges his horse to pull a wagon. The horse refuses saying that to try would be futile because it would flout Newton's third law. The horse concludes that she can't exert a greater force on the wagon than the wagon exerts on her and, therefore, that she won't be able to accelerate the wagon. Convince her to pull.

The forces act on different things. a=f/m. Tell the horse to push backward on the ground to make a bigger force than the wagon exerts.

Ch.6 p.103-108 #71: Your friend says that the law of momentum conservation is violated when a ball rolls down a hills and gains momentum. What do you say?

The law does not include external forces acting on the object.

Ch.13 p.259-263 #5: How does the water pressure 1m below the surface of a small pond compare with the water pressure 1m below the surface of hug lake?

The pressures are the same at the same depth.

Ch.2 p.35-38 #81: Consider a ball at rest in the middle of a toy wagon. When the wagon is pulled forward, the ball rolls against the back of the wagon. Discuss and interpret this observation in term of Newton's first law.

This is due to inertia.

Ch.7 p.126-131 #105: Running a car's air conditioner usually increases fuel consumption. But, at certain speeds, a car with its windows open and with the air conditioner turned off can consume more fuel. Discuss and explain.

With the windows open, the car experiences more air drag.

Ch.2 p.35-38 #25: a bird sitting in a tree is traveling at 30 km/s relative to the Sun. With your feet on the ground, you also travel at the same 30 km/s. do you maintain this speed when your feet leave the ground? What concept supports you answer.

Yes, because when you jump the floor does not move from under you and you land in a different place. You would still land on the same spot you jumped from. For example, a bird still moves at 30km/s relative to the Sun.

Ch.5 p.85-89 #45: Consider the two forces acting on the person who stands still - namely, the downward pull of gravity and the upward support of the floor. Are these forces equal and opposite? Do they form an action-reaction pair?

Yes, you push on Earth and Earth pushes back on you.

Ch.5 p.85-89 #9: Consider the system of a single football. If you kick it, is there a net force to accelerate the system? IF a friend kicks it at the same time with an equal and opposite force, is there a net force to accelerate the system?

Yes. The net force is provided by contact with your foot. If two opposite an equal forces act on the ball, the net force on it is 0 and it will not move.

Ch.8 p.153-159 #21: In terms of center of gravity, support base, and torque, why can't you stand with your heels and back to a wall and then bend over to touch your toes and return to your stand-up position?

Your center of gravity will not be aligned with your support base and you will not be able to counterbalance yourself and you will topple forward.

Ch.2 p.35-38 #33: Different materials, A, B, C, and D, rest on a table. a) Rank how much they resist being set into motion, from greatest to least. b) Rank the support (normal) forces the table exerts on them, from greatest to least.

a) B, A, C, D b) B, A, C, D

Ch.7 p.126-131 #51: The mass and sped do the three vehicles, A, B, and C, are shown. Rank them from greatest to least. a. Momentum b. Kinetic energy c. Work done to bring them up to their respective speeds from rest

a. B, A, C b. C, B, A c. C, B, A

Ch.10 p.201-205 #35: A ball is thrown upward at the velocities and angles shown. From greatest to least, rank them by their a. vertical components of velocity b. horizontal components of velocity c. accelerations when they reach the top of their paths

a. B, C, A, D b. B, D, A, C c. A = B = C = D ASK ABOUT THIS

Ch.6 p.103-108 #39: The balls whose have different masses and speed. Rank the following from greatest to least: a. The momenta b. The impulses needed to stop the balls

a. B, C, D, A b. B, C, D, A

Ch.5 p.85-89 #33: Three identical puck, A, B, and C, are sliding across ice at given speeds. The forces of air and ice friction are negligible. a. Rank the pucks by the force needed to keep them moving, from greatest to least. b. Rank the pucks by the force needed to stop them in these same time interval, from greatest to least.

a. C = B = A b. C, B, A

Ch.4 p.68-73 #57: Three parachutist, A, B, and C, each have reached terminal velocity at the same distance above the ground below. a. From fastest to slowest, rank their terminal velocities. b. From longest to shortest, rank their times to reach the ground.

a. C, A, B b. B, A, C LOOK AT THIS

Ch.7 p.126-131 #53: The roller coaster ride starts from rest at point A. Rank these quantities from greatest to least at each point. a. Speed b. KE c. PE

a. D, B, C, E, A b. D, B, C, E, A c. A, E, C, B, D

Ch.8 p.153-159 #45: To tighten a bolt, you push with a force of 80N at the end of a wrench handle that is .25m from the axis of the bolt. a. What torque are you exerting? b. You move your inward to be only .10m from the bolt. To achieve the same torque, show that you should exert 200N of force. c. Do your answers depend on the direction of your push relation to the direction of the wretch handle?

a. t= .25m(80N) = 20mN b. 20mN=.10m(X) 200N=force c. yes

Ch.3 p.52-56 #9: What is the acceleration of a car moving along a straight road that increases its speed from 0 to 100 km/h in 10s?

a= v/t a= 100km/h / 10s = 10 kms/h/s

Ch.3 p.52-56 #11: When are you most aware of your motion in a moving vehicle: when it is moving steadily in a straight line or when it is accelerating? If you were in a car that moved with absolutely constant velocity (no bumps), would you be aware of motion?

accelerating: yes velocity: no

Ch.13 p.259-263 #27: Place an egg in a pan of tap water. Then dissolve salt in the water until the egg floats. How does the density of an egg compare with that of tap water? With that of saltwater?

denser than fresh and less than saltwater

Ch.13 p.259-263 #39: A 12kg piece of metal displaces 2L of water when submerged. Show that its density is 6000kg/m3. How does this compare with the density of water?

density = 12kg/2L = 6kg/1L x 1000L/m3 = 6000 kg/m3

Ch.7 p.126-131 #41: The second floor of a house is 6m above the street level. How much work is required to lift a 300kg refrigerator to the second story level?

f=ma f= (300kg)(10m/s) = 3,000N w = fd w = (3,000N)(6m) = 18,000J

Ch.6 p.103-108 #79: If a Mack truck and a MiniCooper have a head-on collision, which vehicle experiences the greater force of impact? The greater impulses? The greater change in momentum? The greater deceleration?

force, impulse, and change in momentum = same MiniCooper = deceleration

Ch.5 p.85-89 #43: If you exert a horizontal force of 200N to slide a crate across a factory floor at constant velocity, how much friction is exerted by the floor on the crate? Is the force of friction equal and oppositely directed to your 200N push? If the force of friction isn't the reaction force to your push, what is?

friction = 200N net force = 0 reaction = crate pushes back on you

Ch.10 p.201-205 #59: A circularly moving object requires centripetal force. What supplies this force from satellites that orbit Earth?

gravitation

Ch.2 p.35-38 #57: A jokey hangs stationary at the end of vertical vine. What two forces act on the monkey? Which, if either, is greater?

gravity and tension which are both equal

Ch.7 p.126-131 #115: Does the KE of a car change more when it goes from 10 to 20km/h or 20 to 30km/h?

greater KE speed at greater speed

Ch.10 p.201-205 #17: At what part of an elliptical orbit does an Earth satellite have the greatest sped? The lowest speed?

greatest when closest and lowest when farthest

Ch.2 p.35-38 #13: Consider Nellie hanging at rest in Figure 2.11. If the ropes were vertical, with no angle involved, what would be the tension in each rope?

half of Nellie's weight on each

Ch.6 p.103-108 #51: when you catch a fast-moving baseball with you bare hand, why is it important to extend you hand forward for the catch?

increases time and decreases force

Ch.4 p.68-73 #15: Is acceleration directly proportionally to mass or inversely proportional to mass? Give an example.

inversely proportional

Ch.13 p.259-263 #105: Compared with an empty ship, would a ship loaded with a cargo of styrofoam sink deeper into the water or rise in the water? Discuss.

it floats lower in the water

Ch.3 p.52-56 #13: What did Galileo discover about the amount of speed a ball gained each second when rolling down an inclined plane? What did this say about the ball's acceleration?

it was the same each time: constant

Ch.13 p.259-263 #79: Will a rock gain or lose buoyant force as it sinks deeper in water? Or will the buoyant force remain the same at greater depths?

it will remain the same

Ch.9 p.177-181 #27: If Earth shrank but there was no change in its mass, what would happen to your weight at the surface?

it would increase

Ch.4 p.68-73 #99: If a ball is thrown vertically into the air in the presence of air resistance, would you expect the time during which it rises to be longer or shorter than the time during which it falls?

longer

Ch.6 p.103-108 #7: When you are struck by a moving object, is it favorable that the object makes contact with you over a short time or over a long time? Explain.

momentum is decreased over a long time

Ch.4 p.68-73 #117: Explain whether or not a sheet of paper falls more slowly than one that is wadded into a ball.

more air resistance on the paper that is not wadded

Ch.13 p.259-263 #7: Why does buoyant force act upward on an object submerged in water?

more force with a greater depth and pressure

Ch.6 p.103-108 #53: Many years ago, automobiles were manufactured to be as rigid as piassble, whereas today's autos are deigned to crumple upon impact. Why?

more time, decreases momentum and impact

Ch.9 p.177-181 #11: Would the springs inside a bathroom scale be more compressed or less if you sighed yourself in an elevator that was accelerating upward? Downward?

more up and less down

Ch.2 p.35-38 #77: Two forces act on a parachutist falling in air: the force of gravity and air resistance. If the fall is steady, which no gain or loss of speed, then the parachutist is in dynamic equilibrium. How do the magnitudes of gravitational force and air resistance compare?

must be equal but opposite

Ch.2 p.35-38 #1: what class of motion, natural or violent, did Aristotle attribute to motion of the Moon?

natural

Ch.4 p.68-73 #115: What is the net force acting on a falling 1kg ball in free fall?

net force 10n-2n=8n

Ch.7 p.126-131 #95: If an automobile were to have a 100% efficient engine, transferring all of the fuel's energy to work, would the engine be warm to your touch? Would its exhaust heat vibrate? Would any of the fuel go unused?

no because 100%

Ch.4 p.68-73 #61: Since an object weighs less on the surface of the Moon than on Earth's surface, does it have less inertia on the Moon's surface?

no mass not weight

Ch.9 p.177-181 #15: Why are the ISS occupants weightless when thy a re dimly in the grip of earth's gravity?

no support force

Ch.6 p.103-108 #77: When you are traveling in your car at highway speed, the momentum f a bug is suddenly changed as it splatters onto your window shield. Compared with the change int he momentum of the bug, by how much does the momentum of you car change?

not evident to car; mV for bug = to Mv for car

Ch.6 p.103-108 #23: What is the momentum of a 50kg carton that slides at 4m/s across an icy surface?

p=mv p=50kg(4m/s) = 200kgm/s

Ch.7 p.126-131 #32: Show that 50W of power is required to a brick 100J of Pe in a time of 2s.

p=w/t 50W = 100J/2s

Ch.7 p.126-131 #49: How many watts of power do you expend when you exert a force of 50N that moves a crate 8m in a time interval of 4s?

p=w/t p= 400J/4s = 100W w=fd w=50N(8m) = 400J

Ch.2 p.35-38 #11: According to the parallelogram rule, what quantity is represented by the diagonal of a constructed parallelogram?

resultant vector

Ch.4 p.68-73 #21: How does the direction of acceleration compare with the direction of the net force that produces it?

same direction

Ch.10 p.201-205 #49: Two golfers each hit a ball at the same sped, but one at 60 and one at 30. Which ball goes farther? which hits the ground first?

same distance, 30 lands first because it is in the air for a shorter time

Ch.14 p.277-281 #67: How does the concept of buoyancy complicate the old question "which weighs more: a pound of lead or a pound of feathers?"

same mass, but more buoyancy for lead

Ch.7 p.126-131 #87: Which, if either, has greater momentum: a 1kg moving at 2m/s or a 2kg ball moving at 1m/s? Which has greater KE?

same momentum but the 1kg ball has greater KE

Ch.6 p.103-108 #69: Here are the familiar pair of carts connected by a spring. what are the relative speeds of the carts when the spring is released?

same momentum, twice the mass and half the speed and twice the speed and half the mass

Ch.13 p.259-263 #17: Fill in the blanks: An object denser than water will ... in water. An object less dense than water will ... in water. An object that has the same density as water will ... in water.

sink, float, neither

Ch.6 p.103-108 #1: Which has a greater momentum: a heavy truck at rest or a moving skateboard?

skateboard because it is only moving

Ch.3 p.52-56 #73: A ball tossed upward will return to the same point with the same initial speed when air resistance is negligible. When air resistance in not negligible, how does the return speed compare with its initial speed?

slower

Ch.4 p.68-73 #27: What two principal factors affect the force of air resistance on a falling object?

speed and the frontal area (volume?)

Ch.6 p.103-108 #47: In terms of impulse and momentum, why do mountain climbers favor nylon ropes, which stretch considerably under tension?

stretching ropes increases time while momentum decreases and stop a person does not decrease the impulse, just force

Ch.2 p.35-38 #51: When any object is in mechanical equilibrium, what can be correctly stated about all the forces that act on it? Must the net force necessarily be zero?

the are all equal, yes

Ch.3 p.52-56 #89: Suppose that the three balls shown in Exercise 88 start simultaneously from the tops of the hills. Which one reaches the bottom first? Explain.

the middle because it has a greater acceleration because of the steepness at the beginning

Ch.6 p.103-108 #55: A lunar vehicle is tested on Earth at a speed of 10km/h. When it travels as fast on Moon, is its momentum more, less, or the same?

the same

Ch.4 p.68-73 #83: How much force acts on a tossed coin when it is halfway to it max height? How much force acts on it when it reaches its peak?

the same mg on all points

Ch.8 p.153-159 #13: What is meant by the "lever arm' of torque?

the shortest distance between the applied force and rotational axis

Ch.14 p.277-281 #3: What is the cause of atmospheric pressure?

the weight of air REMEMBER

Ch.13 p.259-263 #9: How does the volume of a completely submerged object compare with the volume of water displace?

they are the same

Ch.8 p.153-159 #39: Calculate the torque produced by the same 50N force when a pipe extends the length of the wretch to .5m.

torque = lever arm x force torque = .5m x 50N = 25mN

Ch.3 p.52-56 #7: If a car moves with a constant velocity, does it also move with a constant speed?

yes

Ch.4 p.68-73 #3: As you increase your push, will friction on the crate increase also?

yes

Ch.8 p.153-159 #25: If you are not wearing a seat belt in a car that rounds a curve and you slid across your seat and slam against a door, what kind of force is responsible for your slid: centripetal, centrifugal, or no force? Why is the correct answer no force?

you are going straight and the car curves into you