Physics Final Exam

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

(10-4) = 6N

Pour a liter of water at 40°C into a liter of water at 20°C and the final temperature of the two becomes

(40+20 =60/2= 30 c) at or about 30 degrees Celsius

A mosquito flying at 3m/s that encounters a breeze blowing at 3m/s in the opposite direction has a speed of

0m/s

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

0m/s2

A block pulled to the left with 15 N and to the right with 5 N at the same time experiences a net force of

10N

A bag of groceries that has a mass of 10 kilograms weighs about _____ N

1kg = 10N 10kg X X= 100N

According to newton, when the distance between two interacting objects doubles. The gravitational force ______

2 squared = 4 = 1/4 (inverse square law) Is one quarter

When a drawn bow of potential energy 40 J is fired, the arrow will ideally have a kinetic energy

40 J

Suzie Skydiver, who weighs 500 N, reaches terminal velocity of 90 km/h. The air resistance on Suzie is then

500N (for every action there is an equal and opposite reaction)

A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the same direction has a speed of

6 m/s

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

6 m/s^2

An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will A) move in the opposite direction at a lower speed B) move in the opposite direction at 20m/s C) move in the opposite direction at a higher speed D) none of the above

A) move in the opposite direction at a lower speed because W=mg and his mass is more than the ball.

The most basic of the sciences of physics, chemistry, and biology is A) physics. B) chemistry. C) biology. D) none of the above

A) physics

A circus diver drops from a high pole into water far below. When he is halfway down A) his kinetic energy and potential energy are equal B) he has gained an amount of KE equal to half his initial PE C) his potential energy has halted D) all the above

All the above

The earliest and most influential Greek philosopher was Aristotle, who among many contributions taught that A) the four elements are earth, water, air, and fire B) violent motion requires a sustained push or pull C) all motion is either natural or violent D) all the above

All the above

When you walk at an average speed of 4 m/s, in 5 s you'll cover a distance of

Average speed = distance / time 4m/s = x / 5 4(5) (5) X= 20 m

The average speed of a horse that gallops 10 kilometers in 30 minutes is___km/hr

Average speed = distance/ time Average speed = 10km/.5hour Average speed = 20km/h

Which of the following has the largest momentum relative to Earth's surface ? A) a mouse running across your room B) a pickup truck speeding along a highway C) the science building on campus D) a Mack truck parked in a parking lot E) a tightrope walker crossing Niagara Falls

B) a pickup truck speeding along a highway

Whether a truck comes to a stop by crashing into a haystack or a brick wall, the impulse is A) greater with the haystack B) both the same C) greater with the brick wall

B) both the same. The impulse remains the same.

A theory in the field of science is A) an educated guess. B) less than a fact. C) a synthesis of a large body of well-tested knowledge. D) unchangeable.

C) a synthesis of a large body of well-tested knowledge

The lower the temperature of an object the A) longer the waves B) lower the frequency of the radiation it emits C) all of these

C) both of these

Which temperature scales have equal sized degrees ?

Celsius to Kelvin

The first scientist to be credited for postulating that Earth circled the sun was

Copernicus

Padded dashboards in cars are safer in an accident than non-padded ones because passengers hitting the dashboard encounter A) shorter time of contact B) increased momentum C) decreased impulse D) lengthened time of contact

D) lengthened time of contact because ⬆️ time of contact ⬇️force.

According to Kepler, the paths of planets around the sun are

Ellipses

A bird flying at 8 km/h in a 6-km/h crosswind has a resultant speed of

F= 8^2 + 6^2 = 100 square root 100= 10km/h

Danny Diver weighs 500 N and steps off a diving board 10 m above the water. Danny hits the water with kinetic energy of

F= w• d F= 500N • 10m F= 5,000J

What is the force of gravity on a 500-N woman standing on Earth's surface?

F=mg F= 500N

A tow truck exerts a force of 3000 N on a car, which then accelerates at 2 m/s2. What is the mass of the car?

F=m•a 3000N = m•2m/s2 /2 /2 1500kg = m

A car has a mass of 1000 kg and accelerates at 2 m/s2. What net force is exerted on the car?

F=m•a F= 1000kg• 2m/s F= 2000N

The total momentum of a flock of identical birds could be zero only if the birds are A) taking off from the ground B) very tired and coming down to rest C) flying in different directions D) flying in the same direction

Flying in different directions. Total momentum =0 because ⬅️+ 4. -4➡️ 4+ -4 = 0

It is correct to say that impulse is equal to A) force multiplied by the distance it acts on B) momentum C) velocity multiples by time D) the corresponding change in momentum

F•t = mVf - mVo (Impulse) (Change in momentum)

The average braking force of a 1000-kg car moving at 10 m/s braking to a stop in 5 s is A) 3000N B) 4000N C) 5000N D) 2000N E) 1000N

F•t = m•v M= 1000kg V= 10m/s t= 5s F• (5) = (1000)(10) 10,000 /5 /5 F= 2000N

According to Newton, the greater the masses go interacting objects the

Greater the gravitational force between them

While a rock thrown upward at 50 degrees to the horizontal rises, neglecting air drag, its vertical component of velocity

Increases

Gelileo taught us that if you roll a ball along a level surface it will

Keep rolling if friction is absent

A same-size iron ball and wooden ball are dropped simultaneously from a tower and reach the ground at the same time. The iron ball has a greater

Momentum

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 A) Equal to its weight divided by its mass B) Equal to its weight C) Equal to urs mass times it's weight D) none of the above

None of the above

Communications and weather satellites always appears the same place in the sky becaus these satellites are

Orbiting the earth with a 24-hour period

A 2-kg ball is held 4 m above the ground. Relative to the ground its potential energy is

PE= m • g • h PE= 2 • 10 • 4 PE= 80J

The power expended doing 100 J of work in 50 s is

Power= energy(j)/time(s) Power = 100/50 Power = 2WATTS

Nellie tosses a ball upward at an angle. Neglecting air resistance, the horizontal component of the initial velocity

Remains constant

While a rock thrown upward at 50 degrees to the horizontal rises, neglecting air drag, its vertical component of velocity

Remains unchanged

Galileo's use of inclined planes allows him to effectively

Slow down the balls change in speed

Which of the following is not a vector quantity

Speed

An object is dropped and freely falls to the ground with an acceleration of 1 g. If it is thrown upward at an angle instead, its acceleration will be

The same, g is constant

In comparison with other fundamental forces, the universal gravitational constant G indicates that gravity is

Very weak

The work you do when pushing a shopping cart twice as far while applying twice the force is

W= 2f • 2d = 4x So four times as much.

The work done in pushing a TV set a distance of 2 m with an average force of 20 N is

W= F•d W= 20N • 2m W= 40 J

The net force on any object in equilibrium is

Zero

A dropped ball gains speed because

a gravitational force acts on it

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 m/s

If an apple experiences a constant net force, it will have a constant

acceleration

Science is a body of knowledge that A) describes order in nature B) condenses knowledge into testable laws C) is an ongoing human activity D) all of the above

all of the above

Facts in the field of science

are changeable

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

continue moving at the same speed

If a volume of air is warmed, it expands. If a volume of air expands, it

cools

Nellie tosses a ball upward at an angle. Neglecting air resistance, the vertical component of the initial velocity

decreases with time to reach the top.

The unit kilowatt-hour is a unit of

energy

The force that propels a cannonball when fired from a cannon is

equal and opposite to the force the ball exerts on the cannon

The force with which Earth pulls on the Moon is

equal in magnitude to the force that Moon pulls on Earth.

When a rocket forces exhaust gases downward, the exhaust gases

exert an upward force on the rocket

Science later greatly advanced when Galileo favored

experiment over philosophical discussions

Pseudoscience is best characterized as being

fake

When you drop a rubber ball on the floor it bounces back. The force exerted on the ball to produce bouncing is by the

floor

Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency of the rock is to

follow a straight-line path

An Earth satellite is simply a projectile

freely falling around the earth

When you touch a hot potato with your finger, energy flows

from the potato to your finger

As a ball bounces from a floor, its acceleration off the floor between bounces is

g

A ball is tossed upward. Neglecting air drag, the acceleration along its path is

g downward

The scientific method is most effective in

gaining, organizing, and applying new knowledge

Suspend your body from a pair of vertical ropes and the tension in each rope will be

half your weight

When Joshua brakes his speeding bicycle to a stop, kinetic energy is transformed to

heat

An educated scientific guess is a

hypothesis

Two objects move toward each other due to gravity. As the objects get closer and closer, the force between them

increases

A sheet of paper can be quickly jerked beneath a container of milk without toppling, which best demonstrates

inertia

If the net force on a cart is tripled, the cart's acceleration

is three times as much

Temperature is most closely related to molecular

kinetic energy

A force is a vector quantity because it has both

magnitude and direction

An object that has kinetic energy must be

moving

To produce an acceleration to a system there

must be a net force on the system

A ball rolled along a horizontal surface maintains a constant speed because

no horizontal forces act on it

The force of Earth's gravity on a capsule in space will lessen as it moves farther away. If the capsule moves to twice its distance, the force toward Earth becomes

one fourth

The mass of a ball moving at 3 m/s with a momentum of 48 kg m/s is

p=m•v 48m/s = m • 3m/s /3 /3 M= 16kg

Compared to the mass of an apple on Earth, the mass of the apple on the Moon is

same

Sun's radiant energy is composed of shorter wavelengths than Earth's due to Sun's greater

surface temperature

Heat energy travels from an object with a high

temperature to an object with a lower temperature

Newton discovered

that gravity is universal

No work is done by gravity on a bowling ball that rolls along a bowling alley because

the force on the ball is at right angles to the ball's motion

To say there is no such thing as only one force means

there must also be a corresponding reaction force

The fact that a thermometer "takes its own temperature" illustrates

thermal equilibrium

Earth pulls on the moon, and the moon pulls on the earth, which tells us that

these two pulls comprise an action-reaction pair.

The kind of molecular motion that mostly relates to the temperature of a substance is

translational motion

A crate of grapes lifted 10 meters gains 200 J of potential energy. If the same crate is instead lifted 20 meters, its gain in potential energy is

twice as much

Nellie tosses a ball upward at an angle. Assuming no air resistance, which component of velocity changes with time?

vertical component

A bloc of wood and a block of copper will feel neither hot nor cold to the touch wen they each have

your temperature

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

zero

A weight watcher who normally weighs 400 N stands on top of a very tall ladder so she is one Earth radius above the Earth's surface. How much would she weigh there?

|_____|______|🌎 1 distance = 2d from earth = 2 squares = 1/4 sooooo 400n • 1/4 = 100N