Physics final study guide

A bicycle travels 15 km in 30 minutes. What is the average speed?

30 km/h

An airplane whose airspeed is 295 km/h flies parallel to the direction of a wind with a speed of 40.0 km/h. What are the two possible speeds of the plane relative to the ground?

335 km/h

65 yards per hour into inches per week

393,120 in/wk

15 years into seconds

473,040,000 sec

A fluid can be either a liquid or a gas

True

In the absence of air resistance, at what other angle will a thrown ball go the same distance as one thrown at an angle of 75 degrees?

a. 15 degrees

when an object reaches terminal velocity its acceleration is.. a. 0 m/s^2 b. 4.9 m/s^2 c. 9.8 m/s^2

a. O m/s^2

An unfortunate bug splatters against the windshield of a moving car. Compared to the deceleration of the car, the deceleration of the bug is a. larger b. smaller c. the same

a. larger

The unit of power is the a. watt b. joule c. newton d. second e. meter

a. watt

What is the resultant of a 3-unit vector and 4-unit vector at right angles to each other?

b. 5 units

The astronomer Copernicus publicly stated in the 1500s that earth

b. revolves around the sun

A girl pulls on a 8-kg wagon with a constant force of 24 N. What is the wagon's acceleration? a. 0.3 m/s^2 b. 8 m/s^2 c. 3 m/s^2 d. 192 m/s^2 e. 24 m/s^2

c. 3 m/s^2

A ball is thrown straight up. At the top of its path its acceleration is...

c. about 10 m/s^2

A vector is a quantity that has...

c. magnitude and direction

Speed is...

d. all of the above

Acceleration is defined as the CHANGE in...

d. velocity divided by the time interval

A man weighing 640 N sits on the floor. He exerts a force on the floor of a. 64 N b. 6400 N c. 6.4 N d. 1280 N e. 640 N

e. 640 N

A scalar quantity has...

only magnitude

850 lbs per week into kg per second

.000634 kg/sec

A 50 kg free-floating astronaut fires 0.10 kg of gas at a speed of 20 m/s from her propulsion pistol. What is the astronaut's recoil speed

.04

At 2 kg blob of clay moving horizontally at 5 m/s has a head on collision with a 4kg blob of clay that moves toward it at 3m/s. What is the speed of the two blobs stuck together immediately after the collision?

.3 m/s

A 7-kg blob of clay moving horizontally at 1 m/s hits a 4-kg blob of clay at rest. What is the speed of the two blobs stuck together immediately after the collision?

.64

A 7kg blob of clay moving horizontally at 1m/s hits a 4-kg blob of clay at rest. What is the speed of the two blobs stuck together immediately after the collision?

.64 m/s

52,647 inches into miles

.83 mi

A couch potato might consume 2 million J of energy in a day. What is the rate of energy consumption in watts?

0.001 J

A 50-kg free-floating astronaut fires 0.10-kg of gas at a speed of 20 m/s from her propulsion pistol. What is the astronaut's recoil speed?

0.04

A 2-kg blob of clay moving horizontally at 5 m/s has a head on collision with a 4-kg blob of clay that moves toward it at 3 m/s. What is the speed of the two blobs stuck together immediately after the collision?

0.3

You toss a ball at 5 m/s straight upward. How much time will the ball take to reach the top of its path?

0.5 sec

What vertical distance can a person with a 0.7 hang time jump?

0.6 sec

What is the hang time of a person who can jump a vertical distance of 0.8 m?

0.8 sec

A 50-kg football player leaps through the air to collide with and tackle a 50-kg player headed towards him, also in the air. If the 50-kg player is heading to the right at 5 m/s and the 50-kg player is heading toward the left at 3 m/s, what is the speed and direction of the tangled players?

1

A 50 kg football player leaps through the air to collide with and tackle a 50 kg player heading toward him,also in the air. If the 50 kg player is heading to the right at 5m/s and the 50 kg player is heading toward the left 3 m/s what is the speed and direction of the tangled players?

1 m/s to the right

1500 feet per second into miles per hour

1,022.73 mi/h

A 50-kg girl and a 25-kg boy face each other on friction-free roller skates. The girl pushes the boy, who moves away at a speed of 3 m/s. What is the girl's speed?

1.5

You push with 15.0 N on a 10.0-kg block and there are no opposing forces. How fast will the block accelerate?

1.5 m/s^2

A certain unbalanced forces give a 10-kg object an acceleration of 5.0 m/s^2. What acceleration would the same force give a 30-kg object?

1.7 m/s^2

A ball is thrown upward. Its initial vertical component of velocity is 30 m/s, and its initial horizontal component of velocity is 10 m/s. What are the horizontal and vertical components of ball's velocity 5 s later?

10 m horizontally

A motorboat is driven across a river at 3.0 km/h at right angles to a current that is flowing at 10.0 km/h. What is the resulting speed of the motorboat?

10.4 km/s

900,000 seconds into days

10.42 days

Assume that a 25-kg ball moving at 2 m/s strikes a wall perpendicularly and rebounds elastically at the same speed. What is the amount of impulse given to the wall?

100

Assume that a 25kg ball moving at 2 m/s strikes a wall perpendicularly and rebounds elastically at the same speed. What is the amount of impulse given to the wall?

100

How much (in newtons) does a 10.0-kg bag of grass seed weigh?

100 N

A stone is dropped from a cliff. After it has fallen 10 m, what is the stone's velocity?

100 m/s^2

What is the maximum resultant possible when adding 2-N force to an 8-N force?

10N

265 pounds into kilograms

119.25 kg

On the surface of Jupiter, the acceleration due to gravity is about 3 times that on Earth. How much would a 0.40-kg rock weigh on Jupiter?

12 N

Kyle throws a ball horizontally from the top of a building that is 5.0 m high. He hopes the ball will reach a swimming pool that is at the bottom of the building, 12.0 m horizontally from the edge the building. If the ball is to reach the pool, with what initial speed must Kyle throw it with?

12 m/s

30 miles per hour into meters per second

13.41 m/s

Two forces of 10-N both act on an object. The angle between the forces is 90. What is the magnitude of their resultant?

14.14 N

9 N up, 3 N down, and 8 N right

154 N

On the surface of Jupiter, the acceleration due to gravity is about 3 times that of Earth. What would be the mass of a 170-kg rock on Jupiter?

170 K

34 miles into feet

179,520 ft

You push with 27 N on a 10-kg chest, and there is a 7-N force of friction. How fast will the chest accelerate?

2 m/s^2

A 10 kg cement block moving horizontally at 2m/s plows into a bank of sand and comes to a stop in 1 s. What is the average impact force on the bank.

20

What speed must you toss a ball straight up so that it takes 4 s to return to you?

20 m/s

A 30-kg block of cement is pulled upward (not sideways!) with a force of 600 N. What is the acceleration of the block?

20 m/s^2

A jet on an aircraft carrier can be launched from 0 to 40 m/s in 2 seconds. What is the acceleration of the jet?

20 m/s^2

A ball is thrown horizontally from the top of a tall cliff. Neglecting air drag, what vertical distance has the ball fallen 2.0 seconds later?

20 meters

Two forces of 10 N both act on an object. The angle between the forces is 90 degrees.

200 N

What is the work done in lifting 60 kg of bricks to a height of 35 m?

2100 J

A 230.0 kg bear grasping a vertical tree slides down at constant velocity. What is the friction force between the tree and the bear?

2300 N

A 6-kg bowling ball moving at 2 m/s bounces off a spring at about the same speed that it had before bouncing. What is the change in momentum of the bowling ball?

24

A 6kg bowling ball moving at 2m/s bounces off a spring at about the same speed that it had before bouncing. What is the change in momentum of the bowling ball?

24

A girl whose weight is 500 N hangs from the middle of a bar supported by two vertical strands of rope. What is the tension in each strand?

250 N

A toy cart moves with a kinetic energy of 30 J. If its speed is tripled, what will its kinetic energy be?

270 J

300 yards to meters

274 m

70 miles per gallon into kilometers per liter

29.84 km/liter

If you push off the ground with a force of 290 N when you jump upward, what force pushes Earth downward?

290 N

130 meters per second into miles per hour

290.73

A 25-kg girl climbs up a tree to a branch 7 m higher in 6 seconds. What is her power output?

292 W

Starting from rest, a car undergoes a constant acceleration of 6 m/s^2. How far will the car travel in the first second?

3 m

A ball is thrown upward. Its initial vertical component of velocity is 30 m/s and its initial horizontal component of velocity is 10 m/s. What is the ball's speed 4 s later?

30 m/s

A 5-N force and a 30-N force act in the same direction of an object. What is the net force on the object?

35N

What is the minimum resultant possible when adding a 5-N force to an 8-N force?

3N

A loaded freight car has 4 times as much mass as an empty freight car. If the loaded car coasts at 5 m/s and collides with and attaches to the empty car at rest, what will be the speed of both cars after the collision?

4

A skateboarder starting from rest accelerates down a ramp at 2 m/s^2 for 2 s. What is the final speed of the skateboarder?

4 m/s

A net force of 2.0 N acts on a 2.0-kg object, initially at rest, for 3.0 seconds. What is the distance the object moves during that time?

4.5 meters

A 70-kg cart moving at 100 km/h collides head-on with an approaching 60-kg cart moving at 30 km/h (in the opposite direction). If the two carts stick together, what will be their speed?

40

What is the average speed of a cheetah that runs 100 m in 4 sec?

40 m/s

What is the average momentum of a 50-kg biker who covers 400 m in 50 s?

400

What is the average momentum of a 50 kg biker who covers 400 m in 50s

400kg*m/s

A loaded freight car has 4 times a much mass as an empty freight car. If the loaded car coasts at 5m/s and collides with and attaches to the empty car at rest, what will be the speed of both cars after the collision?

4m/s

An unbalanced force of 15 N gives an object an acceleration of 3.0 m/s^2. What force would be needed to give it an acceleration of 1.0 m/s^2?

5 N

An apple falls from a tree and 0.5 second later hits the ground. How fast is the apple falling when it hits the ground?

5 m/s

Suppose that you exert 400 N horizontally on a 50-kg crate on a factory floor, where friction between the crate and the floor is 150 N. What is the acceleration of the crate?

5 m/s^2

A staging that weighs 400 N supports two painters. One painter weighs 350 N and the other weighs 400 N. The tension in the right rope is 650 N. Find the tension in the left rope.

500 N

6 N force acting vertically upward and a 4 N force acting horizontally to the right?

52

What is the work done in raising a 90-kg block 6 m vertically?

540 J

A package falls out of a helicopter that is traveling horizontally at 70 m/s. It falls into the water below 8.0 seconds later. Assuming no air resistance, what is the horizontal distance it travels while falling?

560 meters

How much (in newtons) does a 0.60 kg of salami weigh?

6 N

120,800 gallons per month into liters per hour

634.87 liters/hr

A person weighs 650 N. What is the mass of a person?

65 KG

When air resistance on a falling skydiver builds up to 30% of weight of the skydiver, what is the acceleration of the skydiver?

7 m/s^2

How much time does a car with an acceleration of 5 m/s^2 take to go from 5 m/s to 40 m/s?

7 sec

What is the magnitude of the resultant of a 6.0-N force acting vertically upward and a 4.0-N force acting horizontally?

7.2 N or the square root of 52

What is the average acceleration of a car that goes from rest to 60 km/h in 8 seconds?

7.5 km/h/s

The following forces act on an object: 9 N north, 52 N south, and 55 N west. What is the magnitude of the net force?

70 N

What amount of work is done on a wheelbarrow that is pushed 8 m across a floor by a horizontal 90-N net force?

720 J

2678 m into feet

8,783.84 ft

520 miles per second into meters per second

836,800 m/s

88 inches per second into miles per week

840 mi/wk

At what height does a 1000-kg mass have a potential energy of 1 J relative to the ground?

9800 m

A ball is thrown into the air. At the highest point, the ball has zero velocity and zero acceleration.

False

A ball will go farthest if thrown almost horizontally.

False

A quantity that has both magnitude and direction is called a scalar quantity

False

A quantity that has only magnitude is called a vector quantity

False

A quantity that has only magnitude is called a vector.

False

A single vector can be replaced by two vectors that are at right angles to each other. These are called the resultants

False

A unit of acceleration is meters per second.

False

A unit of velocity is the meter.

False

As a ball falls freely, the distance it falls each second is the same.

False

Average speed is defined as the time it takes for a trip divided by the distance.

False

Mass is a vector quality

False

Mass is a vector quantity

False

Objects moving at constant speed in a straight-line path are said to be in static equilibrium

False

The acceleration of an object is inversely proportional to the net force acting on it.

False

The name of the astronomer who first publicly stated that Earth revolves around the sun is Galileo.

False

The pascal is a unit of force

False

The speed of an object dropped in air will continue to increase without limit

False

When a car rounds a corner at a constant speed, its acceleration is zero.

False

When adding two vectors at right angles, the resultant of the vectors is the algebraic sum of the two vectors.

False

Nellie Newton weighs 150 N. Fill in the blanks to show the tension in each rope on the different situation depicted in the pictures.

I50 N, 75 N, 50 N, x2 75 N

You are helping your aunt move a piano on wheels from one room to another. When you push the piano horizontally, it moves at constant speed. What can you say about the piano?

It is dynamic equilibrium

A cement truck of mass 16,000 kg moving at 15 m/s slams into a cement wall and comes to a halt. What is the force of impact on the truck?

Not enough information to solve

Two sets of swings are shown in the picture below. If the children on the swings are of equal weights, the ropes of which swing are more likely to break? Explain.

The one on the right because it has more tension since its horizontal

A force can be simply defined as a push or a pull.

True

An object in static equilibrium is in a state of no motion

True

Any vector can be represented by two other vectors that are at right angles to each other

True

Any vector can be represented by two other vectors that are at right angles to each other.

True

Even though a car is slowing down, it is still accelerating, in the most general definition of acceleration.

True

Friction refers to the force between two surfaces that are sliding past each other.

True

If a hockey puck were to slide on a perfectly frictionless surface, it will eventually slow down because of its inertia.

True

Inertia is the property that every material object has inertia resists changes in an object's state of motion.

True

It is possible for a falling object to have a zero acceleration

True

The combination of all of the forces that act on an object is called the net force

True

The length of a vector represents its magnitude.

True

The rate at which distance is covered is called speed.

True

The rate at which velocity changes with time is called acceleration.

True

The vector sum is called the resultant.

True

Unless stated otherwise, when we discuss the speeds of things, we mean with respect to the center of the universe.

True

Velocity is different from speed in that velocity is speed in a given direction.

True

When we discuss the motion of something, its motion is described relative to something else.

True

Wind velocity can be represented as a vector quantity.

True

A 15-N falling object encounters 15 N of air resistance. The magnitude of the net force on object is a. 0 N b. 15 N c. 30 N d. none of the above

a. 0 N

A ball is thrown straight up. At the top of its path its instantaneous speed is...

a. 0 m/s

A train travels 6 meters in the first second of travel, 6 meters again during the second second of travel, and 2 meters again during the third second. Its acceleration is...

a. 0 m/s^2

You pull horizontally on 50-kg crate with a force of 300-N and the friction force on the crate os 250 N. The acceleration of the crate is a. 1 m/s^2 b. 11 m/s^2 c. 6 m/s^2 d. 0.5 m/s^2

a. 1 m/s^2

How much force is needed to accelerate a 4.0-kg physics book to an acceleration of 3.0 m/s^2? a. 12.0 N b. 1.3 N c. 0 N d. 0.8 N e. 36.0 N

a. 12.0 N

It takes 65 J to push a large box 5 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the box? a. 13 N b. 325 N c. 5 N d. 65 N e. none of the above

a. 13 N

A tow truck exerts a force of 1000 N on a car, accelerating it at 0.5 m/s/s. What is the mass of the car? a. 2000 kg b. 667 kg c. 1000 kg d. 4000 kg e. none of the above

a. 2000 kg

Suppose the force of friction on a sliding object is 30 N. The force needed to maintain a constant velocity is a. 30 N b. more than 30 N c. less than 30 N

a. 30 N

How much power is required to do 10 J of work on an object in 2 seconds? a. 5 W b. 10 W c. 20 W d. 2 W e. 0 W

a. 5 W

Suppose a car is moving in a straight line and steadily increases its speed. It moves from 35 km/h to 40 km/h the first second and from 40 km/h the next second. What is the car's acceleration?

a. 5 km/h/s

How much work is done on a 30-N rock that you lift 2 m? a. 60 J b. 0 J c. 1 J d. 2 J e. 30 J

a. 60 J

A sportscar has a mass of 1500 kg and accelerates at 5 meters a second squared. What is the magnitude of the force acting on the the sportscar? a. 7500 N b. 1500 N c. 300 N d. 2250 N e. none of the above

a. 7500 N

A cannon with a barrel velocity of 140 m/s launches a cannonball horizontally from a tower. Neglecting air resistance, how far vertically will the cannonball have fallen after 4 seconds?

a. 80 m

If you drop a feather and a coin at the same time in a vacuum tube, which will reach the bottom of the tube first?

a. Neither-they will both reach the bottom at the same time

At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first?

a. Neither. They both hit the ground a the same time

Which has the greatest kinetic energy, a car travelling at 30 km/h or a half-as-massive car travelling at 60 km/h? a. The 60 km/h car b. Both have the same kinetic energy c. The 30 km/h car

a. The 60 km/h car

The ratio of useful work output to total work input is called the a. efficiency b. lever arm c. fulcrum d. mechanical advantage e. pivot point

a. efficiency

In the absence of air friction, the vertical component of a projectile's velocity doesn't change as the projectile moves.

a. false

Forces always occur a. in pairs b. in triplets c. as single quantities d. by themselves

a. in pairs

A karate chop delivers a blow of 2500 N to a board that breaks. The force that acts on the hand during this feat a. is 2500 N b. cannot be determined c. is less than 2500 N d. is more than 2500 N

a. is 2500 N

An airplane flying into a head wind loses ground speed, and an airplane flying with the wind gains ground speed. If an airplane flies at right angles to the wind, the groundspeed is...

a. more

In chapter 2, you learned about "hang time," the time a jumper's feet are off the ground in a vertical jump. If the jumper runs horizontally and has the same vertical component of takeoff velocity, hang time will be...

a. no different

A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of work but different amounts of a. power b. energy c. both a and b d. none of the above

a. power

A force of 4 N accelerates a mass of 4 kg at the rate of 1 m/s^2. The acceleration of a mass of 8 kg acted upon by a force of 8 N is a. the same b. twice as much c. half as much d. none of the above

a. the same

Compared to its mass on Earth, the mass of a 10-kg object on the moon is...

a. the same

A tennis ball and a solid steel ball with the same diameter are dropped at the same time. Which ball has the greater force acting on it? a. the steel ball b. they both have the same force acting on them c. the tennis ball

a. the steel ball

As an object falls freely in a vacuum, its..

a. velocity increases

After a cannonball is fired into frictionless space, the amount of force needed to keep it going equals...

a. zero, since no force is necessary to keep it moving

In order to find the components of a vector, you should... a. draw the vector with correct magnitude and orientation b. measure the sides of the rectangle c. draw a rectangle so that the vector is the diagonal d. all of the above

all of the above

A projectile launched horizontally hits the ground in 0.8 seconds. If it had been launched with a much higher speed in the same direction, it would have hit the ground (neglecting Earth's curvature and air resistance) in...

b. 0.8 s

A freely falling object starts from rest. After falling for 1 second, it will have a speed of about...

b. 10 m/s

A car accelerates at 2 m/s^2. Assuming the car starts from rest, how much time does it need to accelerate to a speed of 20 m/s?

b. 10 seconds

A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is a. zero b. 10 times as much as the force on the 1-kg book c. the same as the force on the 1-kg book

b. 10 times as much as the force on the 1-kg book

A jet has a mass of 20,000 kg. The thrust for each of the four engines is 10,000 N. What is the jet's acceleration when taking off? a. 0.5 m/s^2 b. 2 m/s^2 c. 0.3 m/s^2 d. 1 m/s^2 e. none of the above

b. 2 m/s^2

A 11-N falling object encounters 8 N of air resistance. The magnitude of the net force on the object is a. 8 N b. 3 N c. 11 N d. 0 N e. none of the above

b. 3 N

A 15-N force and a 45-N force act on an object in opposite directions. What is the net force on the object? a. 15n b. 30n c. 45n d. 60n e. none of the above

b. 30 n

If a projectile is fired straight up at a speed of 30 m/s, the total time to return to its starting point is about...

b. 6 seconds

Suppose you take a trip that covers 180 km and takes 3 hours to make. Your average speed is...

b. 60 km/h

Which requires more work: lifting a 50-kg sack vertically 4 meters or lifting a 25-kg sack vertically 8 meters? a. Lifting the 25 kg sack b. Both require the same amount of work c. Lifting the 50 kg sack

b. Both require the same amount of work

Which of the following would NOT be considered a projectile?

b. a cannonball rolling down a slope

Suppose an object is in free fall. Each second the object falls...

b. a larger distance than in the second before

If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by...

b. about 10 m/s

You are on a frozen pond, and the ice starts to crack. If you lie down on the ice and begin to crawl, this will a. increase the total force on the ice b. decrease the pressure on the ice c. increase the pressure on the ice d. decrease the total force on the ice

b. decrease the pressure on the ice

Pressure is defined as a. force per time b. force per area c. time per area d. velocity per time e. distance per time

b. force per area

When a car's speed triples, its kinetic energy a. triples b. increases by 9 times c. remains the same d. increases by four times e. none of the above

b. increases by nine times

How does acceleration of an object change in relation to its mass? It is a. directly proportional b. inversely proportional c. Acceleration doesn't depend on mass at all.

b. inversely proportional

Compared to its weight on Earth, a 10-kg object on the moon will weigh..

b. less

A scalar is a quantity that has...

b. magnitude

An object that has kinetic energy must be a. elevated b. moving c. falling d. at rest

b. moving

The unit of pressure is a. newtons b. newtons per square meter (or pascals) c. meters per second squared d. the meter e. the newton

b. newtons per square meter (or pascals)

Kinetic energy of an object is equal to a. one half the product of its mass times its speed b. one half the product of its mass times its speed squared c. its mass multiplied by its speed d. its mass multiplied by its acceleration squared e. its mass multiplied by its acceleration

b. one half the product of its mass times its speed squared

The amount of potential energy possessed by an elevated object is equal to a. the value of the acceleration due to gravity b. the distance it is lifted c. the force needed to lift it d. the power used to lift it

b. the distance it is lifted

An unfortunate bug splatters against the windshield of a moving car. Compared to the force of the car on the bug, the force of the bug on the car is a. larger b. the same c. smaller d. need more information to say

b. the same

A larger truck and a small car traveling at the same speed have a head-on collision. The vehicle to undergo the greater change in velocity will be a. the large truck b. the small car c. neither-both are the same

b. the small car

A tennis ball and a solid steel ball with the same diameter are dropped at the same time. In the absence of air resistance, which ball has the greater acceleration? a. the tennis ball b. they both have the same acceleration c. the steel ball

b. they both have the same acceleration

Galileo found that a ball rolled down one inclined plane would roll how far up another inclined plane?

b. to nearly its original height

In the absence of air friction, the horizontal component of a projectile's velocity doesn't change as the projectile moves.

b. true

What is needed to describe a vector quality?

both magnitude and direction

The vertical height attained by a basketball player who achieves a hang time of a full one second is about...

c. 1.2 m

A ball is thrown straight upward at 10 m/s. Ideally (no air resistance), the ball will return to the thrower's hand with a speed of...

c. 10 m/s

When a woman stands with two feet on a scale, the scale reads 240 N. When she lifts on foot, the scale reads a. more than 240 N b. less than 240 N c. 240 N

c. 240 N

A cannonball is launched from the ground at an angle of 30 degrees above the horizontal and a speed of 30 m/s. Ideally (no air resistance) the ball will land on the ground with a speed of...

c. 30 m/s

In the absence of air resistance, the angle at which a thrown ball will go the farthest is...

c. 45 degrees

A cannonball is fired a some angle into the air. In the first second it moves 5 meters horizontally. Assuming it doesn't hit the ground and air resistance is negligible, how far does it move horizontally in the next second?

c. 5 m

A car starts from rest and after 7 seconds it is moving at 42 m/s. What is the car's average acceleration?

c. 6 m/s^2

A cannonball is launched horizontally from a tower. If the cannon has a barrel velocity of 60 m/s, where will the cannonball be 1 second later?(Neglect air resistance)

c. 60 m downrange

A freely falling object starts from rest. After falling for 6 seconds, it will have a speed of about...

c. 60 m/s

Which of the following would exert the most pressure on the ground? a. A woman standing in running shoes b. A woman standing on skis c. A woman standing in high-heel shoes

c. A woman standing in high-heel shoes

Whenever an object exerts a force on another object, the second object exerts a force of the same magnitude, but in the opposite direction to that of the first object. a. Always false b. Sometimes true c. Always true

c. Always True

Energy is changed from one form to another with no net loss or gain. a. Always false b. Sometimes true c. Always true

c. Always true

At what part of a path does a projectile have a minimum speed?

c. At the top of its path

Suppose you are in a car that is going around a curve. The speedometer reads a constant 30 miles per hour. Which of the following is NOT true?

c. Your velocity is constant

When something falls to the ground, it accelerates. This acceleration is called the acceleration due to gravity and is symbolized by the letter g. What is the value of g on Earth's surface?

c. about 10 m/s^2

In the absence of air resistance, objects fall at constant...

c. acceleration

The law of inertia applies to...

c. both moving and nonmoving objects

If Nellie Newton pushes an object with twice the force for twice the distance, she does a. twice the work b. eight times the work c. four time the work d. the same work

c. four times the work

An object that has kinetic energy must have a. a force applied to maintain it b. acceleration c. momentum d. none of the above

c. momentum

If the velocity of a moving object doubles, then what else doubles? a. acceleration b. kinetic energy c. momentum d. all of the above e. none of the above

c. momentum

The unit of work is a. force b. acceleration c. momentum d. impulse e. none of the above

c. momentum

If the force of gravity suddenly stopped acting on the planets, they would...

c. move in straight lines tangent to their orbits

If you drop a feather and a coin at the same time in a tube filled with air, which will reach the bottom of the tube first?

c. the coin

A heavy person and a light person parachute together and wear the same size parachutes. Assuming they open their parachutes at the same time, which person reaches the ground first? a. the light person b. Neither- they both reach the ground together c. the heavy person

c. the heavy person

Acceleration is defined as...

c. the rate at which velocity itself changes

After a rock that is thrown straight up reaches the top of its path and is starting to fall back down, its acceleration is (neglecting air resistance)

c. the same as when it was at the top of its path

A ball is thrown upwards and caught when it comes back down. In the absence of air resistance, the speed of the ball the instant before it's caught would be...

c. the same speed it had when thrown upwards

The horizontal component of a projectile's velocity is independent of...

c. vertical component of its velocity

The force required to maintain an object at a constant speed in free space is equal to...

c. zero

Sue can easily lift a 45.0-N rock with the help of a lever. When she pushes down with 5.0 N of force, she lifts the rock 0.1 meters. How far does she move her arms to do this? a. 0.1 m b. 0.5 m c. 5.0 m d. 0.9 m e. 9.0 m

d. 0.9 m

Suppose a moving car has 1500 J of kinetic energy. If the car's speed triples, how much kinetic energy will it then have? a. 500 J b. 1000 J c. 1500 J d. 13,500 J e. 4500 J

d. 13,500 J

A 90-N object moves at 1 m/s. Its kinetic energy is a. 1 J b. more than 90 J c. 90 J d. 4.5 J

d. 4.5 J

A baseball is hurled into the air at an angle of 30 degrees above the horizontal and lands on a target that is at the same level as that where the baseball started. The baseball will also land on the target if it is thrown at an angle of...

d. 60 degrees

How many joules of work are done on a crate when a force of 10 N pushes it 7 m? a. 1 J b. 1 J c. 10 J d. 70 J e. 7 J

d. 70 J

How much farther will a car travelling at 100 km/s skid than the same car travelling at 50 km/s? a. Half as far b. The same distance c. Twice as far d. Four times as far e. Five times as far

d. Four times as far

If the force acting on the cart doubles, what happens to the cart's acceleration?

d. It doubles

In order to find the components of a vector, you should...

d. all of the above

One possible unit of speed is...

d. all of the above

The acceleration produced by a net force on an object is a. in the same direction as the net force b. inversely proportional to the mass of an object c. directly proportional to the magnitude of the net force d. all of the above e. none of the above

d. all of the above

When representing velocity as a vector, ...

d. all of the above

A pulley system can a. change the direction of a force b. multiply the force c. increase the amount of work done d. both a and b e. both b and c

d. both a and b

An object at rest may have a. velocity b. momentum c. speed d. energy e. none of the above

d. energy

A ball is thrown into the air at some angle. At the very top of the ball's path, its velocity is...

d. entirely horizontal

In physics, work is defined as a. distance divided by time b. force divided by time c. force divided by distance d. force times distance e. force times time

d. force times distance

An object is dropped and falls freely to the ground with an acceleration of g. If it is thrown upward at an angle instead, its acceleration would be...

d. g downward

According to Newton's third law, if you push gently on something, it will push a. gently on something else b. on you only if you aren't moving c. on something only under the right conditions d. gently on you

d. gently on you

When you look at the speedometer in a moving car, you can see the car's...

d. instantaneous speed

A projectile is fired horizontally in a vacuum. The projectile maintains its horizontal component of speed because it...

d. is not acted on by any horizontal forces

Potential Energy is the energy an object has because of its a. size b. temperature c. density d. location e. speed

d. location

If you lift two loads up one story, how much work do you do compared to lifting just one load up one story? a. one half as much b. the same amount c. one quarter as much d. twice as much e. four times as much

d. twice as much

Accelerations are produced by a. accelerations b. velocities c. masses d. unbalanced forces e. none of the above

d. unbalanced forces

Power is defined as the a. force on an object times the distance the object moves b. force on an object divided by the time the force acts c. work done times the time taken to do that work d. work done on an object divided by the time taken to do the work e. distance divided by the time taken to move that distance

d. work done on an object divided by the time taken to do the work

Suppose a small plane can fly at 170 km/h relative to the surrounding air. Suppose also that there is a 60 km/h tailwind. How fast does the plane move?

e. 230 km/h

How much power is expended if you lift a 60 N box 4 meters in 1 second? a. 4 W b. 15 W c. 60 W d. 0 W e. 240 W

e. 240 W

A jumbo jet cruises at a constant velocity which the total thrust of the engines on the jet is 40,000 N. How much air resistance acts on the jet? a. 80,000 N b. 60,000 N c. 0 N d. 20,000 N e. 40,000 N

e. 40,000 N

An arrow in a bow has 90 J of potential energy. Assuming no loss of energy to heat, how much kinetic energy will it have after it has been shot? a. 90 J b. 0 J c. 180 J d. 70 J e. 45 J

e. 45 J

Suppose a cart is being moved by a force. If suddenly a load is dumped into the cart so that the cart's mass doubles, what happens to the cart's acceleration?

e. It halves

As a pendulum swings back and forth a. kinetic energy is transformed into potential energy b. at the end points of its swing, its energy is all potential c. potential energy is transformed into kinetic energy d. at the lowest part of its swings, its energy is all kinetic e. all of the above

e. all of the above

Equilibrium occurs when.... a. all forces acting on the object are balanced b. the sum of the +x forces on the object equal the sum of the -x forces c. the net force on the object is zero d. the sum of the upward forces equals the sum of the downward forces e. all of the above

e. all of the above

The law of inertia states that an object...

e. all of the above

The ratio of output force to input force of a simple machine is called the a. efficiency b. fulcrum c. pivot point d. lever arm e. mechanical advantage

e. mechanical advantage

A heavy object and a light object are released from rest at the same height and time in a vacuum. As they fall, they have equal a. momenta b. weights c. energies d. all of the above e. none of the above

e. none of the above

If you lift one load up two stories, how much work do you do compared to lifting one load up only one story? a. one half as much b. four times as much c. one quarter as much d. the same amount e. twice as much

e. twice as much

What amount of work can a 500-W motor do in 3 minutes?

idk

A clothesline is stretched between two trees. A tire hangs in the middle of the line and the two halves of the line make equal angles with the horizontal. The tension in the line is...

is more than half the tire's weight

If possible, determine the power expended when a barbell is raised 5.0 m in 2 s.

not possible

The weight of a person can be represented by a vector that acts.... a. in a direction that depends on where the person is standing b. perpendicular to the ground underneath the person c. parallel to the ground d. straight down, even when the person is standing on a hill e. all of the above

straight down, even if the person is standing on a hill.

Your dog Milo is lying on the floor in the living room. Describe the forces acting on him. What is the net force?

upward push downward push-gravity Equilibrium

Briefly distinguish between vectors and scalars, giving examples of each.

vectors- magnitude and direction ex. speed Scalar- magnitude ex. mass

What would be the safest way to put up a clothesline?

with some slack in the line