Physics Exam 2 - Practice Test

Ninety-five percent of light incident on a mirror is reflected. How much of the initial incident light is finally reflected from 8 mirrors in succession? Sketch the mirrors.

(.95)(.95)(.95)(.95)(.95)(.95)(.95)(.95 x 100) = 66.34%

If the greenhouse effect on Earth were absent, the Earth's average temperature would be about

-18 ℃

100 g of 100 ℃ steam will completely melt ____ g of 0 ℃ ice.

. (100g)(540 cal/g) = q1 (q=mLv = -54000) (1cal/g℃)(100g)(-100℃) = q2 (q=mct) = -10000 q1+q2=mLf total heat LOST = 54000+10000=64000=(m)(80 cal/g) m=800 g

A 50-N object falling air experiences 45 N air resistance. The acceleration of this is falling body is

1 m/s

A 1-ton blimp hovers in air. The buoyant force acting on it is

1 ton

A wave having a frequency of 1000 Hz vibrates at

1000 cycles per second

A woman who normally weights 400 N stands on top of a very tall ladder so she is one earth-radius above earth's surface what is her weight there?

100N

A shopping cart moves with a kinetic energy of 40 J. If it moves at twice the speed, its kinetic energy is

160 J

Bat chirp travels at the speed of sound in air and its echo is heard after the chirp. The distance to the lunch is

170 meters

If a power plant is 30% efficient, and the transmission system that delivers power to consumers is 60% efficient, then the overall efficiency is

18%

A car moving at 50 km/h skids 20m with locked brakes. How far will it skid if its initial speed is 150 km/h?

180m

A wave oscillates up and down two complete cycles each 1 s. If the wave travels an average distance of 6 m in 1 s, its wavelength is

3m

The amount of light reflected from the front surface of common window glass is about

4%

increasing the temperature of 50 grams of water by 1ºC requires

50 calories

In raising a 5000-N piano with a pulley system, for every 1 m of rope pulled down, the piano rises 0.1 m. Ideally, this means the force needed to lift the piano is

500N

A stone is thrown horizontally from the top of a cliff. One second after leaving your hand it drops a vertical distance of

5m

A sandbag is motionless in outer space. A second sandbag with 2 times the mass moving 9 m/s collides with it and they both stick together and move at a speed of

6 m/s

A wave travels an average distance of 6 m in 1 s. What is the wave's velocity?

6 m/s

A floating leaf oscillates up and down four complete cycles each 2/3 of a second as a water wave passes by. What is the wave's frequency?

6Hz

Ninety-five percent of light incident on a mirror is reflected. How much light is reflected from four mirrors in succession?

81%

The flight of a blimp best illustrates

Archimedes' principle

On which temperature scale is 0 the freezing point of water?

Celsius

Which requires more energy?

Changing 1 gram of 100 ℃ water to 100 ℃ steam

A crystal has a refractive index 1.574 as a gift. You figure out the speed of light in quartz is ___% its speed in vacuum

N=C/V 🡪 1.574=(3 x 10^8 m/s) / V m/s 🡪 (1.574V/1.547V) = (3 x 106^8/ 1.574) 🡪 V= (1.91 x 10^8 m/s) / (3 x 10^8) = 63.5%

Which requires more work on the brakes of a car?

Slowing down from 100 km/h to 70 km/h

The temperature of 70.0 g of 75oC water mixed with 50.0 g of 10oC water is ______ oC to 3 significant figures. Sketch a graph of temperature versus time if the thermometer was first in hot water, then in cold water, and finally in the mixture..

Tf=(TC)(MC) + (TN) (Mn) / (Mc + Mn) Tf= (75C) (70g) + (10C) (50g) / (70g+50) = 47.9C

Which of these has a higher frequency than visible light?

Ultraviolet

The temperature of 50.0 g pf 68.1 ℃ mixed with ____ g of 10.2 ℃ water is 41.2 ℃. Sketch a graph of temp vs time if it was first in hot water, then in cold water, and finally in the mixture. Find the mass of the 10.2 ℃ water to 3 sig figs.

Use Tf=Mc*Tc + Mh*Th/Mc + Mh (mc)(10.2℃)+(50.0g)(68.1℃)/(mc)+(50.0g)=(41.2℃) mc=43.4g

A tube resonates at 439.5 Hz. Another tube twice as long, made of the same material and having the same diameter as the first tube resonates at ______ Hz (to two significant figures).

V= (2D)/t 🡪 (439.5 HZ)/(1) = 2(D)/2 seconds 🡪 (2D)/(2) = (439.5)/2 seconds = 219.75M

Which of the following occupies the smallest percentage of the electromagnetic spectrum?

Visible light

Which of the following expands most when the temperature is lowered? Equal volumes of

Water at 4 ℃

A large block of wood and a small block of iron each register 2000 N on a scale. Taking buoyancy of air into accounted, which has the greater mass?

Wood

The gush of steam that issues from the escape valve of a pressure cooker is relatively cool

above the opening where the expansion is prominent

temperature of water rises when 2.00 cal are added. it will rise the same when 8.38J

added

Without air resistance, a projectile fired horizontally at 8 km/s from a mountaintop will

all of the above

In perceiving its environment, a dolphin makes use of

all of the above (the Doppler effect, echoes and ultrasounds)

The loudness of a musical sound is a measure of the sound wave's

amplitude

A sonic boom can NOT be produced by

an aircraft flying slower than the speed of sound

If you were caught in freezing weather with only a candle for warmth, you would be warmer in

an igloo

Pour a liter of 40 ℃ water into a liter of 20 ℃ water and the final temperature will be

at or about 30 ℃

Newton's law of cooling applies to objects that are

both (cooling and warming)

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

both (decreased force contact and increased time of contact)

A wave is a vibration in

both (time and space)

The density of water at 4 ℃ will slightly decrease when it

both (warms and cools)

A nutritionist in the United States measures the food energy in units of

calories

a red-hot piece of iron will cool faster in a

cold room

As water in a confined pipe speeds up, the pressure it exerts against the inner walls of the pipe

decreases

A tutor will be correct in saying that velocity and acceleration are

different concepts

A Doppler effect occurs when a source of a sound moves

either (towards or away)

A shock wave is produced when the speed of the object

exceeds speed of sound in air

If the temperature of a sample of 4°C water slightly decreases, the sample of water

expands

Convection occurs in

fluids

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 with the force to stop the car, the force to stop the truck is

greater

Scientific equations in a conceptual course are mainly

guides to thinking about the relationships between concepts

The moderate temperatures of islands throughout the world has mainly to do with water's

high specific heat capacity

The direction of natural processes is from states of

higher order to lower order

If a non-rotating object has no acceleration, then we can say for certain that is

in mechanical equilibrium

a wave is a vibration

in time and space

Your room gets messier day by day. In this case entropy is

increasing

The Earlybird communication satellite hovers over the same point on Earth's equator indefinitely because

its orbital period is 24 hours

Heat energy is measured in units of

joules & calories

Relative to average speed in air, the average speed of a beam of light in glass is

less

Hot sand cools off faster at night than plants and vegetation, which indicates the specific heat capacity for sand is

less than that for plants

Atmospheric refraction makes the daylight hours

longer

A sound wave is a

longitudinal wave

Glass in a florist's greenhouse blocks radiation of

low frequency

Two identical freight cars roll without friction towards each other, in opposite directions, on a level track. One car rolls at 4.4 m/s and the other rolls at 3.3 m/s. After the cars collide, they couple and roll together with a speed of ____ m/s.

m1v1+m2v2=(m1+m2)(v) m(4.4m/s)+m(-3.3m/s)=2mv m(1.1)=2mv 1.1=2v v=0.55 m/s in the direction of the 4.4 m/s car

A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill the heavy truck has greater

momentum

If the running speed of Fast Freda doubles, what also doubles is her

momentum

More disorder means

more entropy

Refraction causes the bottom of a swimming pool to appear

more shallow

A freely falling object has a downward speed of 40 m/s at one instant. Exactly 1 s later its speed will be

more than 45 m/s

An Earth satellite is in an elliptical orbit. The satellite travels fastest when it is

nearest to Earth

Consider two planets in space that gravitationally attract each other. If the mass of both planets is doubled, and the distance between them is also doubled, then the force between them is

none

Tangential velocity is velocity

parallel to surface of the earth

Light will not pass through a pair of Polaroids when their axes are

perpendicular

A good heat conductor is a

poor insulator

Complementary colors are two colors that

produce white light when added

as a ball falls, the action force is the pull of Earth's mass on the ball. The reaction force is the

pull of ball's mass on earth

Suppose a gun were made of strong lightweight material with a pellet that is more massive than the gun. Then firing speed is greater for the

recoiling gun

The average speed of light is greatest in

red glass

A stone is thrown horizontally from the top a cliff. 2.5 seconds after leaving your hand it drops a vertical distance of?

s=1/2at^2 (½)(10)(2.5)^2 = 31.25 m

A car travelling at 10 km/h strikes a bug that splatters on the windshield. The force of impact is greater on the

same for both

Which law of thermodynamics addresses the direction of heat flow?

second

The higher the frequency of a wave, the

shorter the wavelength

the explanation for all types of refraction involves change in

speed

A friend says that a can of beverage will cool faster in the coldest part of a refrigerator. Knowledge of Newton's law of cooling

supports statement

The attraction of a person's body towards Earth is called weight. The reaction to this force is

the person's body pulling on Earth

Compared to the density of water, the density of a fish is

the same

Compared with the speed of light in a vacuum, the speed of light in the empty space between molecules in glass is

the same

Light is incident upon a pane of window glass at a particular angle. The angle of emerging light is

the same

Which law of thermodynamics states that no system can reach absolute zero?

third

Suspend a pair of ping pong balls from two strings so there is a small space between them. If you blow air between the balls, they will swing

towards each other

Polarization is a property of

transverse waves

If the same quantity of heat is added to both a 1-liter and a 2-liter container of water, the temperature change of water in the 1-liter container will be

twice

If you walk toward a mirror at a certain speed, the relative speed between you and your image is

twice your speed

A change in pressure at any point in a confined fluid at rest is transmitted

undiminished to all points of the fluid

A bat chirps to locate a tasty lunch. The chirp travels at 340 m/s and its echo is heard by the bat 1.6 s after the chirp. The bats lunch is ___ m from it (to 2 sig figs)

v=2d/t refractive340m/s=2d/1.6s 2d=544 d=272 m BUT TO 2 SIG FIGS 270 m/s

A hypothesis that is scientific must have test for proving it

wrong

The color humans are most sensitive to is

yellow-green