8th grade Science Unit 2 Test

How does radiation help treat cancer?

It heats up the cancer cells and weakens them

A farmer places an unhatched egg under a heat lamp. How does radiation help the egg?

It keeps the eggs warm until they hatch

What must be true about two objects if heat is flowing between through them?

The objects must be different temperatures

Ixchelt burns her tongue when she takes a sip of hot coffee from her mug. Which part of this example represents heat?

The thermal energy moving from the coffee to her tongue

Which factors affect heat transfer between a warm and a cool substance?

the amount of time of contact, the are of contact, and the specific heats of the substance

Which refers to a diagram that shows thermal energy being released by objects?

thermogram

The human body stores chemical energy from digested food. Some of the chemical energy converted into mechanical energy when the body moves. Which statement best supported by this information?

Digested food is a source of potential energy

What are the two main types of energy?

kinetic and potenial

Which is equal to a temperature of 50*F?

10*C

An object has a velocity of 8 m/s and a kinetic energy of 480 J. What is the mass of the object?

15 kg

Kyle has a mass of 54 kg and is joggin at velocity of 3 m/s. What is Kyle's kinetic energy?

243 J

What is the kinetic energy of a ball with a mass of 0.5 kg and a velocity of 10 m/s?

25J

A 40 kg dog is sitting on top of a hillside and has a potential energy of 1,568 J. What is the height of the hillside?

4.0m

A roller coaster with a potential energy of 235, 200 J sits at the tio if a 30 m high hill. What is the mass of the roller coaster?

800 kg

A sled is at rest at the top of a slope 2 m high. The sled has a mass of 45 kg. What is the sled's potential energy?

882 J

Andrea listed some properties of electromagnetic waves: 1. transfer thermal energy by radiation 2. can tranfer energy over great distance 3. need matter to transfer energy through 4. are disturbances that carry energy Which best describes Andrea's error?

Electromagnetic wave can transfer energy through empty space

Why is thermal energy from the sun transferred to earth through electromagnetic waves instead of any other type of thermal energy transfer?

Electromagnetic waves can travel through empty space

Mintu wants to increase the heat transfer between a metal iron and another piece of metal he wants to shape. He decides to increase the time the two metals are in contact, use a larger metal iron, and use a new metal material with a higher specific heat. Where is Mintu's error?

Mintu should have chosen a material with a lower specific heat.

Which refers to the amount of heat required to change temperature of 1 gram of a substance by 1 C and is related to the chemical composition of the substance?

Specific heat

The diagram shows the movement of particles for two substances. Which best compares the temperatures of the substances?

Substance X has the highest temperature because its particles have more kinetic energy

Sayid recorded the temperatures of four substances in a chart. W- 12 X - 18 Y- 9 Z- 20 Which conclusion is best supported by the data?

The particles in a substance W have a lower average kinetic energy than the particles in substance X

Hot coffee in a mug cools over time and the mug warms up. Which describes the energy in this system?

Thermal energy from the coffee is transferred to the mug

The diagram shows the scales used for recording temperatures. The labels of the scales are missing. Water boils W-212 X-100 Y-373

W- Fahrenheit X- Celsius Y- Kelvin

Olivia is on a swing at the playground. At which point is her kinetic energy increasing and her potential energy decreasing? W X Y Z

X

Allison drew a diagram to illustate radiation. Which labels should replace the X and Y?

X: Hot Y: Cold

The table shows information about four objects resting at the top of a hill. Which object is on the tallest hill?

Z

Which activity directly converts energy from the sun into chemical energy?

a bean plant making its own food to grow

Which substance has the most thermal energy and will have the most heat flow from it?

a nuclear reactor core (1000*C)

Which material would result in the least amount of energy transfer?

a reflector that is light in color and smooth

Which refers to a material that takes energy of a wave when the wave hits it?

absorber

Which is the correct order of materials in terms of reflectivity, from least to greatest?

black asphalt, brown soil, beige sand, white paper

What is the overall energy transformation in a coal-fired power plant?

chemical to electrical

Which substance is most likely to heat up faster?

copper (specific heat of .39 /g * C

Juan measured the temperature of salt water. He then added 273 to the measured value. Which conversion is Juan most likely doing?

degrees Celsius to kelvins

The human body stores chemical energy from digested food. Some of the chemical energy is converted into mechanical energy when the body moves. Which statement best supported by this information?

digested food is a source of potential energy

Car manufacturers use radiation for which task?

drying paint

Hedea made a study chart about nuclear energy. Which best describes the error in Hedea's chart>

fission and fusion convert nuclear energy to both radiant and thermal energy

Which best describes the direction of heat?

from a warmer substance to a cooler substance

If a cup of coffee is 90*C and a person with a body temp of 36*C touches it, how will heat flow between them>

from the cup to the hand

Which shows the potential energy of particles in three substances, from least to greatest?

gas, liquid, solid

Which of these actions would increase heat transfer between two objects?

increasing the area of their contact

The total energy in a system is 675 J. The kinetic energy changes from 296 J to 432 J. Which statement best describes the potential energy of this system?

it changes from 379 J to 243 J

Alana summarized what happens when a ball sitting on top of a grassy hill rolls down the hill. The motionless ball has potential energy. Once the ball starts to roll down the hill, new kinetic energy is made. As the ball rolls across the grass, it slows down. The kinetic energy of the ball is converted to other forms of energy. Which best describes Alana's error?

kentic energy is made, it is a result of energy transformation

The diagram shows a baseballs motion. Which statement is best supported by the diagram>

maximum potential energy is at point R

Barbara is converting 78°F to degrees Celsius. First, she subtracts 32 from 78. What is the next step?

multiply 46 by 5/9

Which best describes a difference between energy transformations in power placnts and dams?

only power plants use fossil fuels to transform energy

Plants are responsible for a very important energy transformation, as shown. Which energy transformation does the picture best illustrate?

radiant to chemical

Solar-powered cars use energy from the sun to work. A panel on the car absorbs light energy from the sun, which generates an electrical current. This electrical current, in turn, allows the car to move. Which shows the correct order of energy transformations that take place in a solar paneled car?

radiant, electrical, mechanical

Two examples of energy transformations are shown Lamp and fire. The energy transformations are smiliar because they both involve transformations that

result in radiant energy

Which is an example of radiation?

snowman and the sun

A thermometer is placed in water in order to measure the water's temperature. What would cause the liquid in the thermometer to drop?

the kinetic energy of the water molecules decreases

What happens when heat is removed from water?

the kinetic energy of the water particles decreaes

The diagram shows a swinging pendulum. Which best explains what happens to the motion of the pendulum due to the law of conservation of energy?

the mechanical energy transforms to thermal energy as the pendulum slows and eventually stops moving

Cindy pours cold milk into a hot bowl of oatmeal and then stirs it with a room temp spoon. Which substance will have heat flow from it to the other substances?

the oatmeal

The diagram shows a ball resting at the top of a hill. Which statement best describes the energy in this system?

the potential energy in the system is greatest at X

Taro stated that when someone hits a golf ball with a club, the amount of energy the ball has changes, the amount of energy that the club has changes, and the total energy of the system that includes the ball and the club increases. Which best explains Taro's error?

the total energy of the system remains the same

A burner on a stove produces ______

thermal energy

Which statement best describes heat and thermal energy?

they represents different concepts

Which two factors are used to calculate the kinetic energy of an object?

velocity and mass

Which shows the temperatures of three substances, in order, from greatest to least?

water vapor, water, ice