Science Midterm

A moving freight car slams into another identical freight car at rest. The two cars stick together and move along the track. The KE of the coupled cars compared with the initial KE of the first car is...

less

Microscopic ice slush in a glass of water tends to make the entire slush water...

less dense

Substances are composed of tiny particles. Temperature is related mostly to the particles...

average KE

science and technology are...

basically different from each other.

Why is the kelvin scale the most accurate of three temperature scales?

because it starts at the lowest point of temperature, absolute zero

A ball is projected into the air with 900 J of kinetic energy which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is...

less than 900 joules

If a poor absorber of radiation were a good emitter, its temperature would be...

less than its surroundings

Metals are both good heat and electrical conductors due to...

looseness of outer electrons in metal atoms

A substance that heats up relatively quickly has a...

low specific heat capacity

A theory is supported mainly by...

many experiments

The language of science is...

mathematics

A 10-ohm resistor carries 10 amps. The voltage across the resistor is...

more than 10

A cat and a mouse run down the hallway with the same KE. The faster moving one is the...

mouse

When you comb your hair and electrons transfer from your hair to the comb, your comb acquires a charge that is...

negative

If air were a better conductor than it is, at nighttime the Earth would be...

not appreciably different in temperature

If you push for an hour against a stationary wall, you do no work...

on the wall

When we say charge is conserved, we mean that charge can...

only be transferred from one place to another

dependent variable

outcome

The science that is basic to the others is...

physics

A good heat conductor is a...

poor insulator

When you brush a cat and scrape electrons from its fur, the change of the cat's fur becomes...

positive

The transfer of heat energy through the form of light rays is called...

radiation

If molecules in a sample of gas moved so they completely missed each other, the gas's temperature would...

remain unchanged

A high temperature source radiates relatively ______ wavelengths

short

The higher the temperature of an object, the...

shorter the wavelengths it radiates

Electric power, like all forms of power, is measured in...

watts

All objects continuously emit radiant energy. Why then doesn't the temperature of all objects continuously decrease?

when an object emits radiant energy, it also absorbs radiant energy

The net charge of an atom is equal to...

zero if the atom is electrically neutral

A woman lifts a box from the floor. She then moves with a constant speed to the other side of the room, where she puts it down. How much work does she do on the box while walking across the floor at a constant speed?

zero joules

After a car is raised in a service station, we say the car has increased... a. elastic potential energy b. chemical energy c. kinetic energy d. none of the above

d. none of the above

The decision to wear dark clothing during the winter months is wise because...

dark colors absorb heat

As a hot iron ring cools, the diameter of the hole...

decreases

An empty truck traveling at 10 km/h has kinetic energy. How much kinetic energy does it have when loaded so that its mass and speed are both doubled?

eight times the KE

The density of water at 4°C will slightly decrease when it's...

either cooled or warmed

All surfaces that absorb radiant energy...

emit it as well

When a gas condenses, it _______ energy

emits

In general, good absorbers of electromagnetic radiation are also good _____________

emitters

What do electrical power companies deliver to customers?

energy

Pseudoscience

fake science

The pupil of your eye is black because light that enters your eye...

is absorbed

The charge of an electron...

is always negative

To say that an object is electrically polarized is to say

its charges have been rearranged

The purpose of the ground wire in an appliance is to...

leak excess charge away

During a very cold winter, water pipes sometimes burst because...

water expands when freezing

The lowest temperature possible is...

-273°C

Lettering on the top part of a lightbulb reads, "100 W 120 V." When properly used, the current in the bulb is...

0.8 amps

Exert 1N for a distance of 1m in 1s and you deliver a power of...

1 W

When you do 100 J of work on a sled that slides without friction, its KE increases by...

100 J

How much work is required to raise a 100-kg crate a vertical distance of 3m in a time of 2s?

1500 W

How much work is done on a 200-kg crate that is hoisted 2m in a time of 4s?

4000 joules

A brand-new shiny sports car at the top of a vertical cliff has a PE of 100mJ relative to the ground below. Unfortunately, a mishap occurs and it falls over the edge. When it's halfway to the ground its KE is...

50 mJ

A diver a top a high diving board has a PE of 100mJ relative to the water below. When the diver is half way to the water, the diver's KE is...

50mJ

Does a good insulator prevent heat from escaping or slow its passage?

A good insulator simply slows the passage of heat. Since it's a good insulator, it is a poor conductor, meaning it does not let heat through easily.

What equation in most directly useful for solving a problem that asks for the distance a speeding vehicle skids in coming to a stop?

Fd=🔺(1/2mv ^2)

A circus performer diving off a tall pole has just as much kinetic energy as potential energy relative to the ground, when she...

Is half way to the bottom

Calculate the work done in lifting a 500 N barbell 2.2 m above the floor. What is the PE of the barbell when it's lifted to this height? What's the KE of the barbell when it's dropped to the ground?

KE =1100 joules

What change in KE does an airplane experience on takeoff if it's moved a dístance of 500m by a sub stained net force of 5000 N?

KE=2,500,000

A 20N block falls freely from rest from a point 1.5m above the ground. What is the KE upon hitting the ground?

KE=30 joules

Why can you predict the temperature of the bottom of any lake in New England during the winter time?

Lakes freeze from top to bottom. For deep water, the winter isn't long enough to reduce the entire pond to 4°C. Any 4°C water lies at the bottom. Because of the water's high specific heat and poor ability to conduct heat, the bottom of deep bodies of water in cold regions remains at a constant 4°C year round.

You toss a ball back and forth in a high-flying airplane. Does the KE of the ball relate to the speed of the airplane?

No, because anything inside the plane is part of a system, so it's all moving relative to the plane, not individually.

For hypothesis to be specific, it must be...

Testable

thermal inertia

The ability of a material to maintain its temperature; based on mass

Consider molecules of hydrogen gas (tiny) and oxygen (bigger) in a gas mixture that have the same KE. Which molecules have the greatest average speed?

The hydrogen molecules have the greatest speed because they are smaller than the oxygen molecules. They have a large difference in mass.

Great adventures in science occurred with the invention of...

The printing press

In addition to being an organized body of knowledge about nature, science is also a...

The study of nature's rules

Water vapor changes phase when it changes into snow. Does this phase tend to warm up or cool the surrounding air?

This change tends to warm the surrounding air because when changing from a gas to a solid, it releases energy into the atmosphere, causing the average KE to increase along with temperature.

When you reduce the voltage in a simple electric circuit, you reduce the...

current

To receive an electric shock there must be...

a difference in voltage across part or all of your body

Which of the following normally warms up slower when heat is applied? a. water b. glass c. iron d. wood

a. water

When a liquid boils/evaporates, it ________ energy

absorbs

When a solid is changed to a liquid phase, the solid...

absorbs energy

The kinetic theory of matter states that atoms and molecules are...

always in random motion

Which of these is a scientific hypothesis?

an atom is the smallest bit of matter in a material

Which has a greater amount of thermal energy: an iceberg or a cup of steaming hot coffee?

an iceberg because it contains way more mass than the hot cup of coffee; thermal energy is affected by potential and kinetic energy, so mass has more of an impact than temperature

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

at or about 30°C

independent variable

variable that is manipulated

Hot water will cool to room temperature faster in a...

black pot, rather than a silver pot

Heat energy is measured in units of...

both joules and calories

Mechanical energy applies to...

both potential and kinetic energy

Ice has a lower density than water because ice is...

composed of open-structured ice crystals

The transfer of heat energy from one substance to another that are touching or within a substance is called...

conduction

A substance may absorb heat energy by the process of...

conduction, convection, and radiation

The transfer of heat energy in a fluid is called...

convection

Transfer of heat among air and water molecules causing weather patterns happens by...

convection

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

cools

When two identical cars, one traveling twice as fast as the other, brake to a stop with old-fashioned brakes, the faster car will skid...

four times as far

A model airplane moves twice as fast as another identical model airplane. Compared with the kinetic energy of the slower airplane, the kinetic energy of the faster airplane is...

four times as much

When you touch a piece of ice with your finger, energy flows...

from your finger to the ice

The sun's radiant energy is composed of shorter wavelengths than the earth's because the sun...

has a higher temperature than the earth

When a car brakes to a stop, unless it is a hybrid, its kinetic energy is transformed to...

heat

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

high specific heat capacity

Heat a copper wire and its electric resistance...

increases

Your toes feel warmer on a rug than on a tile floor because the rug...

is a better insulator than tile

A water-filled cup held in a flame, will not catch on fire because...

the paper cup can't become appreciably hotter than the water it contains

Electric charge will flow in an electric circuit when it's complete and when...

there is a difference in voltage

A measure of total energy of particles in a substance is...

thermal energy

Heat is simply another word for...

thermal energy that flows from hot to cold

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

thermal equilibrium

When work is done twice as quickly, then the power expended is...

twice

Raising a heavy load requires work. Raising it twice as high requires...

twice the work