Physics Final

A 10-N falling object encounters 10 N of air resistance. The net force on the object is

0 N

a 5000-kg freight car moving at 2 m/s runs into a 10,000-kg freight car at rest. They couple upon collision and move away as one body at

1/3 m/s

The force of friction on a sliding object is 10 newtons. The applied force needed to maintain a constant velocity is

10 N

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

10 m/s

A care accelerates at 2 meters per second per second. Assuming the car starts from rest, how much time does it need to accelerate to a speed of 30 m/s

15 seconds

A tow truck exerts a force of 3000 N on a car, accelerating it at 2 meters per second per second. What is the mass of the car?

1500 kg

If a projectile is fired straight up at a speed of 10 m/s, the total time to return to its starting position is about

2 seconds

An object at rest near the surface of a distant planet starts to fall freely. If the acceleration there is twice that of the Earth, its speed one second later would be

20 m/s

If a freely falling object were somehow equipped with a speedometer on a planet where the acceleration due to gravity is 20 m/s/s, then its speed reading would increase each second by

20 m/s

A 4 kg ball has a momentum of 12 kg m/s. What is the ball's speed?

3 m/s

A 500-N parachutist opens his chute and experiences an air resistance force of 800 N. The net force on the parachutist is (N and direction)

300 N upward

A karate chop delivers a blow of 3000 N to a board that breaks. The force that acts on the hand during this event is

3000 N

A horse gallops a distance of 20 kilometers in a time of 30 minutes. Its average speed in kilometers per HOUR is

40 km/h

A man weighing 800 N stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is

400 N

Calculate your average speed if you run 50 meters in 10 seconds

5 m/s

A 5-kg fish swimming at a speed of 1 m/s swallows an absent-minded 1-kg fish at rest. The speed of the larger fish after this lunch is

5/6 m/s

A skydiver, who weighs 500 N, reaches terminal velocity of 90 km/h. The air resistance on the diver is then

500 N

A 10-N falling object encounters 4 N of air resistance. The net force on the object is

6 N

If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is

6 km/h/s

If a car accelerates from rest at 2 meters per second per second, its speed 3 seconds later will be about

6 m/s

At one instant an object in free fall is moving downward at 50 meters per second. One second later its speed should be about

60 m/s

An object is dropped from rest an falls freely. After 7 seconds, calculate its instantaneous speed

70 m/s

Calculate the distance (in km) that Harry runs if he maintains an average speed of 8 km/h for 1 hour

8 km

A 1-kf mass at the Earth's surface weighs

9.8 N

Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has the same a. mass b. weight c. volume d. all of these e. none of these

E. none

Every object continues in its state of rest or of uniform motion in a straight line, unless compelled to change that state by forces impressed upon it. This is a statement of

Newton's First Law (Inertia)

The acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object. This statement is

Newton's Second Law

Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. This statement is

Newton's Third Law

If an object's mass is decreasing while a constant force is applied to the object, the acceleration a. increases b. decreases c. stays the same

a. increases

The mass of a pet turtle that weighs 10 N is

about 1 kg

Hang from a pair of gym rings and he upward support forces of the rings will always

add up to equal your weight

According to Newton's law of inertia, a railroad train in motion should continue going forever even if its engine is turned off. We never observe this because railroad trains

always have forces that oppose their motion

An object is propelled along a straight-line path in space by a force. If the mass of the object somehow becomes twice as much, its acceleration a. quadruples b. halves c. doubles d. stays the same

b. halves

Arnold Strong and Suzie Small each pull very hard on opposite ends of a massless rope. The greater force on the rope is exerted by

both the same

A skydiver steps from a helicopter and falls for a few seconds until he reaches his terminal velocity. Thereafter, until he open his parachute, his acceleration a. increases b. decreases c. is zero d. is constant

c. is zero

While an object near the Earth's surface is in free fall its a. mass decrease b. acceleration increases c. velocity increases d. mass increases

c. velocity increases

If an object moves with constant acceleration, its velocity must

change by the same amount each second

If no external forces are acting on a moving object, it will (relating to velocity)

continue moving at the same velocity

An archer shoots an arrow. Consider the action force to be the bowstring against the arrow. The reaction to this force is the a. friction of the ground against the archer's feet b. air resistance against the bow c. combined weight of the arrow and the bowstring d. arrow's push against the bowstring e. grip of the archer's hand on the bow

d. arrow's push against the bowstring

Wheras Aristotle relied on logic in explaining nature, Gaileo relied on

experiment

The newton is a unit of

force

In order to catch a ball, a baseball player extends his hand forward before the impact of the ball and then lets it ride backward in the direction of the ball's motion. Doing this reduces the _______ because

force of impact- time of impact is increased

A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared to the force that stops the car, the force needed to stop the track is the same, greater, or smaller?

greater

Padded dashboards in cars are safer in an accident than nonpadded ones because an occupant hitting the dash has

increased time of impact

When you are in the way of a fast-moving object and can't get out of its way, you will suffer a smaller force of impact if you decrease its momentum over a short or long time, or the same?

long time

A force is a vector quantity because it has both

magnitude and direction

A kilogram is a measure of an object's

mass

Two objects have the same size and shape, but one is much heavier than the other. When they are dropped simultaneously from a tower, they reach the ground at the same time, but the heavier one has a greater (momentum, speed, or acceleration)

momentum

A large metal ball is shot from a cannon with a short barrel. If the same ball were to be shot from a cannon with a longer barrel, its muzzle velocity would be more, less, or the same?

more

Twelve seconds after starting from rest, an object falling freely will have a speed of

more than 100 m/s

An astronaut, floating alone in outer space, throws a baseball. If the ball floats away at a speed of 20 meters per second, the astronaut will move in what direction and a higher, same, or lower speed?

move in the opposite direction, but at a lower speed

An object in mechanical equilibrium is an object

moving with constant velocity, at rest, and no acceleration

An object's weight may properly be expressed in units of

newtons

Compared to falling on a stone floor, a wine glass may not break when it falls on a carpeted floor because

stopping time is longer on the carpet

A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. This best demonstrates that

the milk carton has inertia

Compared to the MASS of a certain object on Earth, the MASS of the same object on the moon is

the same

A car traveling at 100 km/hr strikes an unfortunate bug and splatters it. The force of impact is

the same for both

An object is propelled along a straight-line path by a force. If the net force were doubled, the object's acceleration would be a. half as much b. twice as much c. four times as much d. the same

twice as much

A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is

zero

A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is

zero

When a falling object has reached its terminal velocity, its acceleration is

zero

A sack of potatoes weighing 200 N falls from an airplane. As the velocity of fall increases, air resistance also increases. When air resistance equals 200 N, the sack's acceleration in meters per second per second is

zero

Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?

zero

A car has a mass of 1000 kg and accelerates at 2 meters per second per second. What is the magnitude of the net force exerted on the car?

2000 N

Hang from a pair of gym rings and the upward support force of the rings will always a. add up to equal your weight b. each be half your weight c. each be equal to your weight

a. add up to equal your weight

A player hits a ball with a bat. The action force is the impact of the bat against the ball. The reaction to this force is the a. force that the ball exerts on the bat b. weight of the bat c. weight of the ball d. grip of the player's hand against the ball e. air resistance on the ball

a. force that the ball exerts on the bat

A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. The reaction to this force is the a. force the glove exerts on the ball b. player's grip on the glove c. muscular effort in the player's arm d. friction of the ground against the player's shoes

a. force the glove exerts on the ball

Strange as it may seem, it is just as hard to accelerate a car on a level surface on the moon as it is here on the Earth. This is because a. the mass of the car is independent of gravity b. the weight of the car is independent of gravity c. Not true, a car can accelerate easier on the moon than Earth

a. the mass of the car is independent of gravity

If more horizontal force is applied to a sliding object than is needed to maintain a constant velocity a. the object accelerates in the direction of the applied force b. the friction force increases c. the object accelerates opposite the direction of the applied force d. two of the above e. none of the above

a. the object accelerates in the direction of the applied force

It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft?

about 180 m

A package falls off a truck that is moving at 30 m/s. Neglecting air resistance, the horizontal speed of the package just before it hits the ground is

about 30/s

A ball is thrown upwards. Neglecting air resistance, what initial upward speed does the ball need to remain in the air for a TOTAL time of 10 seconds?

about 50 m/s

Disregarding air resistance, objects fall with constant

acceleration

If the mass of an object does not change, a constant net force on the object produces constant

acceleration

If your automobile runs out of fuel while you are driving, the engine stops but you do not come to an abrupt stop. The concept that most explains why is

inertia

Whenever the net force on an object is zero, its acceleration...

is zero

The scientist to first introduce the concept of inertia was

Galileo

If a projectile is fired straight up at a speed of 10 m/s, the time it takes to reach the top of its path is about

1 second

A car accelerates at 2 meters /s/s. Assuming the car starts from rest, how far will it travel in 10 s?

100 m

An object falls freely from rest on a planet where the acceleration due to gravity is 20 meters per second squared. After 5 seconds, the object will have a speed of

100 m/s

A baseball player bats a ball with a force of 1000 N. The reaction force that the ball exerts against the bat is

1000 N

An object is pulled northward by a force of 10 N and at the same time another force of 15 N pulls it southward. The magnitude of the resultant force on the object is

5 N

Which has the greater mass? a. an automobile battery b. a box of crackers c. both have the same

A. Auto battery

Your weight is a. equal to your mass b. the gravitational attraction force between you and the Earth c. a property of mechanical equilibrium d. all of these

B. the gravitational attraction force between you and the Earth

While a car travels around a CIRCULAR track at a constant speed, its a. acceleration is zero b. inertia is zero c. velocity is zero

D. None of the above

a push on a 1-kg brick accelerates it. Neglecting friction, to equally accelerate a 10-kg brick, one would have to push with a. one-tenth the amount of force b. 10 times as much force c. 100 times as much force d. just as much force

b. 10 times as much force

When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, you make the time of the impact about 10 times as great as for a stiff-legged landing. In this way the average force your body experiences is a. about 10 times as great b. about 1/10 as great c. less than 1/10 as great d. more than 1/10 as great

b. about 1/10 as great

If an object of constant mass experiences a constant net force, it will have a constant a. speed b. acceleration c. position d. velocity e. more than one of the above

b. acceleration

Your friend says that the heavyweight champion of the world cannot exert force of 50 N on a piece of tissue paper with his best punch. The tissue is held in midair- no wall, no tricks You- a. disagree b. agree

b. agree

an object following a straight-line path at constant speed a. has a net force acting upon it in the direction of motion b. has zero acceleration c. has no forces acting on it

b. has zero acceleration

For an action force, there must be a reaction force that is a. is slightly smaller in magnitude than the action b. is exactly equal in magnitude c. is slightly larger in amplitude than the action force d. always acts in the same direction

b. is exactly equal in magnitude

A ball is thrown upwards and caught when it comes back down. In the presence of air resistance, the speed with which is caught is always a. the same as the speed it had when thrown upwards b. less than the speed it had when thrown upwards c. more than the speed it had when thrown upwards

b. less than the speed it had when thrown upwards

As a ball falls, the action force is the pull of the Earth on the ball. The reaction force is the a. acceleration of the ball b. pull of the ball's mass on the Earth c. air resistance acting against the ball

b. pull of the ball's mass on the Earth

A rifle recoils while firing a bullet. The speed of the rifle's recoil is small because a. momentum is mainly concentrated in the bullet b. rifle has much more mass than the bullet c. force against the rifle is smaller than against the bullet d. momentum of the rifle is smaller

b. rifle has much more mass than the bullet

The difference between impulse and impact force involves the a. mass and its effect on resisting a change in momentum b. time the force acts c. difference between acceleration and velocity d. distance the force acts

b. time the force acts

The force required to maintain an object at a constant velocity in free space is equal to a. the mass of the object b. zero c. the weight of the object d. the force required to stop it e. none of these

b. zero

A ball tossed vertically upwards rises, reaches its highest point, an then falls back to its starting point. During this time the acceleration of the ball is always a. opposite its velocity b. directed upward c. directed downward d. in the direction of motion

c. directed downward

A rock weighs 30 N on Earth. A second rock weighs 30 N on the moon. Which of the two rocks has the greater mass?

the one on the moon

A ball is thrown upwards and returns to the same position. If air resistance is neglected, compared with its original speed after release, its speed when it returns is about

the same

When a rock thrown straight upward gets to the exact to of its path, its velocity and acceleration...

velocity is zero and its acceleration is about 10 meters per second per second