1.
What is the process by which heat energy gets to Earth from the Sun?
Correct Answer
B. Radiation
Explanation
Radiation from the Sun, which is more popularly known as sunlight, is a mixture of electromagnetic waves ranging from infrared (IR) to ultraviolet rays (UV). It of course includes visible light, which is in between IR and UV in the electromagnetic spectrum.
2.
Which of the following best explains why the end of a spoon sticking out of a cup of hot water also gets hot?
Correct Answer
B. The heat from the hot water is conducted to the spoon handle.
Explanation
We can understand why the end of the spoon gets hot by once again thinking about molecules.
The fast-moving molecules of water in the coffee bump into the part of the spoon that is next to the hot liquid. This makes the metal molecules of the spoon vibrate harder so that the metal heats up. Quickly the vibrations are passed on, from molecule to molecule, up the handle of the spoon.
3.
Diving into the ocean, as you go deeper, the water gets colder because
Correct Answer
A. The saltiest water is always coldest and sinks to the bottom.
Explanation
Cold water has a higher density than warm water. Water gets colder with depth because cold, salty ocean water sinks to the bottom of the ocean basins below the less dense warmer water near the surface. The sinking and transport of cold, salty water at depth combined with the wind-driven flow of warm water at the surface creates a complex pattern of ocean circulation called the 'global conveyor belt.'
4.
Ms. Lee heats up a pot of water on her stove. Water heated up at the bottom of the pot flows to the top of the pot. The colder water at the top sinks. As the water moves, heat flows from the hotter water to the colder water. Which of the terms describes this method heat transfer ?
Correct Answer
B. Convection
Explanation
Convection is the concerted, collective movement of groups or aggregates of molecules within fluids (e.g., liquids, gases) and rheids, through advection or through diffusion or as a combination of both of them. Convection of mass cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids. Diffusion of heat can take place in solids, but that is called heat conduction. Convection can be demonstrated by placing a heat source (e.g. a Bunsen burner) at the side of a glass full of a liquid, and observing the changes in temperature in the glass caused by the warmer ghost fluid moving into cooler areas.
5.
Patti used a steel wrench to work on her bicycle on a hot, sunny day. She left the wrench on the hot concrete for an hour, then returned, to find the wrench very hot to touch. What is the BEST explanation for how the wrench got so hot?
Correct Answer
D. Heat transferred from the concrete to the wrench.
Explanation
Heat transfer is the exchange of thermal energy between physical systems. The rate of heat transfer is dependent on the temperatures of the systems and the properties of the intervening medium through which the heat is transferred. The three fundamental modes of heat transfer are conduction, convection and radiation. Heat transfer, the flow of energy in the form of heat, is a process by which a system changes its internal energy, hence is of vital use in applications of the First Law of Thermodynamics. Conduction is also known as diffusion, not to be confused with diffusion related to the mixing of constituents of a fluid.
6.
Samuel is investigating a substance to determine what it is made of. He studies the physical and chemical properties of the substance. Which of these properties of the substance is a chemical property ?
Correct Answer
D. How well the substance burns
Explanation
Chemical properties are characteristics of a material that become evident when the material undergoes a chemical reaction or chemical change. People cannot observe chemical properties by simply viewing or touching a sample of the material; the actual structure of the material must be changed in order for people to observe the chemical properties.
Chemical Property Examples
Chemical properties can only be established by changing a substance’s chemical identity, and are different from physical properties, which can be observed by viewing or touching a sample.
The internal qualities of a substance must be altered to determine its chemical properties. For example:
Flammability - How easily something will burn or ignite, is a chemical property because you can’t tell just by looking at something how easily it will burn. Fire testing is done to determine how difficult or easy it will be to get a certain material to burn.
Information about flammability is used in building codes, fire codes, insurance requirements, and storing, handling, and transporting highly flammable materials.
Heat of Combustion - This chemical property is the amount of energy that is released as heat when a substance is burned with oxygen.
Examples of this chemical property is a calorie which converts to energy within the body and the amount of heat generated by the burning of various fuels.
7.
For a snack, Bill and Mary heated milk in a pot on the stove for hot chocolate and popped some popcorn in the microwave oven. How did they transfer heat energy to make these snacks?
Correct Answer
C. Heating milk by conduction; popping popcorn by radiation
Explanation
Conduction is the transfer of energy through matter from particle to particle. It is the transfer and distribution of heat energy from atom to atom within a substance. For example, a spoon in a cup of hot soup becomes warmer because the heat from the soup is conducted along the spoon. Conduction is most effective in solids-but it can happen in fluids. Fun fact: Have you ever noticed that metals tend to feel cold? Believe it or not, they are not colder! They only feel colder because they conduct heat away from your hand. You perceive the heat that is leaving your hand as cold.
Radiation: Electromagnetic waves that directly transport ENERGY through space. Sunlight is a form of radiation that is radiated through space to our planet without the aid of fluids or solids. The energy travels through nothingness! Just think of it! The sun transfers heat through 93 million miles of space. Because there are no solids (like a huge spoon) touching the sun and our planet, conduction is not responsible for bringing heat to Earth. Since there are no fluids (like air and water) in space, convection is not responsible for transferring the heat. Thus, radiation brings heat to our planet.
8.
Convert 20°C to °F.
Correct Answer
B. 68°F
Explanation
°F to °C Deduct 32, then multiply by 5, then divide by 9
°C to °F Multiply by 9, then divide by 5, then add 32
9.
Fuels which do not exist in nature are known as
Correct Answer
C. Synthetic fuel
Explanation
Synthetic fuel or synfuel is a liquid fuel, or sometimes gaseous fuel, obtained from syngas, a mixture of carbon monoxide and hydrogen, in which the syngas was derived from gasification of solid feedstocks such as coal or biomass or by reforming of natural gas.
10.
The area behind the dam where water is stored
Correct Answer
D. Reservoir
Explanation
A reservoir (etymology: from French réservoir a "storehouse" [1]) is a storage space for fluids. These fluids may be water, hydrocarbons or gas. A reservoir usually means an enlarged natural or artificial lake, storage pond or impoundment created using a dam or lock to store water. Reservoirs can be created by controlling a stream that drains an existing body of water. They can also be constructed in river valleys using a dam. Alternately, a reservoir can be built by excavating flat ground and/or constructing retaining walls and levees.
11.
The average speed of the molecules of a substance
Correct Answer
A. Temperature
Explanation
Temperature is a degree of hotness or coldness the can be measured using a thermometer. It's also a measure of how fast the atoms and molecules of a substance are moving. Temperature is measured in degrees on the Fahrenheit, Celsius, and Kelvin scales.
12.
The internal motion of atoms is called
Correct Answer
C. Heat Energy
Explanation
Heat energy is the result of the movement of tiny particles called atoms, molecules or ions in solids, liquids and gases. Heat energy can be transferred from one object to another, and the transfer or flow due to the difference in temperature between the two objects is called heat.
13.
Joe put a cheeseburger sealed in a plastic bag into the microwave, without much air in the bag. After it cooked, the bag was full of air. Where did the air come from?
Correct Answer
D. It came from a chemical reaction whereby energy from the microwave creates O2 molecules.
Explanation
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another.[1] Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes may occur.
14.
The bulb of a thermometer is placed in your mouth. Which of the following explains why the level of the liquid rises in the thermometer?
Correct Answer
C. The liquid expands when heated.
Explanation
Key Concepts
The way a thermometer works is an example of heating and cooling a liquid.
When heated, the molecules of the liquid in the thermometer move faster, causing them to get a little further apart. This results in movement up the thermometer.
When cooled, the molecules of the liquid in the thermometer move slower, causing them to get a little closer together. This results in movement down the thermometer.
15.
The transfer of energy by electromagnetic waves (photons), through space.
Correct Answer
C. Radiation
Explanation
Radiation from the Sun, which is more popularly known as sunlight, is a mixture of electromagnetic waves ranging from infrared (IR) to ultraviolet rays (UV). It of course includes visible light, which is in between IR and UV in the electromagnetic spectrum.
16.
The amount of energy that is changed into the desired form.
Correct Answer
B. Efficiency
Explanation
Energy conversion efficiency (η) is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the useful output may be electric power, mechanical work, light (radiation), or heat.
17.
The energy of an object that is deformed under tension and compression
Correct Answer
A. Elastic potential energy
Explanation
Elastic potential energy is Potential energy stored as a result of deformation of an elastic object, such as the stretching of a spring. It is equal to the work done to stretch the spring, which depends upon the spring constant k as well as the distance stretched.
18.
Which of the following could best be used to demonstrate energy being transformed from electricity to heat?
Correct Answer
C. A toaster
Explanation
An electric heater is an electrical device that converts electric current to heat. The heating element inside every electric heater is an electrical resistor, and works on the principle of Joule heating: an electric current passing through a resistor will convert that electrical energy into heat energy.
19.
Two jars are placed inside an insulated box. One jar contains ice water and the other contains hot soup. What will happen to the two liquids?
Correct Answer
D. The hot soup will lose heat and the ice water will gain heat.
Explanation
The second law of thermodynamics states that the total entropy of an isolated system always increases over time, or remains constant in ideal cases where the system is in a steady state or undergoing a reversible process.
20.
The ratio of an object’s mass to its volumeis its
Correct Answer
B. Density
Explanation
The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ (the lower case Greek letter rho), although the Latin letter D can also be used.