1.
Touching hot spoon
Correct Answer
A. Conduction
Explanation
Conduction is the transfer of heat through direct contact between two objects or substances. In this case, when a person touches a hot spoon, heat is transferred from the spoon to the person's hand through conduction. The heat energy travels from the hot spoon to the cooler hand, causing the hand to feel the sensation of heat. Convection and radiation are not applicable in this scenario as they involve heat transfer through fluids or electromagnetic waves, respectively.
2.
Air circulation in house
Correct Answer
B. Convection
Explanation
Convection is the process of heat transfer through the movement of a fluid, such as air or water. In the context of air circulation in a house, convection occurs when warm air rises and cool air sinks, creating a continuous flow of air. This movement of air helps to distribute heat evenly throughout the house, ensuring that all areas are adequately heated or cooled. Therefore, convection is the most appropriate answer for explaining air circulation in a house.
3.
Light waves traveling through empty space
Correct Answer
C. Radiation
Explanation
Light waves traveling through empty space is an example of radiation. Radiation refers to the transfer of energy through electromagnetic waves, such as light, without the need for a medium. In this case, light waves can travel through the vacuum of empty space because they do not require any particles or matter to propagate. This is in contrast to conduction and convection, which both require a medium, such as a solid or fluid, for energy transfer.
4.
Thermal energy always is transferred from the hotter object to the colder object.
Correct Answer
A. True
Explanation
This statement is based on the principle of the second law of thermodynamics, which states that heat flows spontaneously from a hotter object to a colder object. This is because heat is a form of energy that tends to spread out and equalize the temperature between objects. Therefore, thermal energy is always transferred from the hotter object to the colder object.
5.
The transfer of energy in fluids or gases
Correct Answer
B. Convection
Explanation
Convection is the transfer of energy in fluids or gases through the movement of the particles themselves. In convection, heat is transferred by the circulation of currents within the fluid or gas. This process occurs because warmer particles are less dense and rise while cooler particles sink. This movement of particles allows for the transfer of heat from one area to another. Therefore, convection is the correct answer as it describes the transfer of energy in fluids or gases.
6.
When hot air rises and cool air sinks, this is an example of ....
Correct Answer
B. Convection
Explanation
When hot air rises and cool air sinks, it is an example of convection. Convection is the transfer of heat through the movement of a fluid, such as air or water. In this case, the hot air rises because it is less dense than the cool air, creating a convection current. This process is commonly observed in natural phenomena such as the rising of hot air balloons or the circulation of air in a room when a heater is turned on.
7.
A boy sits to the side of a campfire. He is 10 feet away, but still feels warm. This is an example of ...
Correct Answer
C. Radiation
Explanation
The boy feeling warm even though he is 10 feet away from the campfire suggests that the heat is being transferred through radiation. Radiation is the transfer of heat energy through electromagnetic waves, which can travel through empty space. In this case, the heat from the campfire is being emitted as infrared radiation and reaching the boy, making him feel warm. Conduction and convection involve the transfer of heat through direct contact or movement of a fluid, respectively, which do not apply in this scenario.
8.
You walk barefoot on the hot street and it burns your toes. This is an example of...
Correct Answer
A. Conduction
Explanation
When you walk barefoot on a hot street, the heat from the street is transferred to your toes through direct contact. This transfer of heat through direct contact is known as conduction. Conduction occurs when there is a temperature difference between two objects in contact, causing the heat to flow from the hotter object to the cooler one. In this case, the hot street is the hotter object, and your toes are the cooler one, resulting in the transfer of heat and the burning sensation.
9.
The air in the hot air balloon is heated and circulates. This is an example of ...
Correct Answer
B. Convection
Explanation
The heating of the air in the hot air balloon causes it to become less dense and rise. As the heated air rises, it creates a circulation pattern within the balloon. This circulation of air is known as convection. Convection is the transfer of heat through the movement of a fluid, in this case, the heated air.
10.
Energy in motion
Correct Answer
B. Kinetic
Explanation
The correct answer is "kinetic" because kinetic energy refers to the energy possessed by an object due to its motion. It is the energy that an object has when it is in motion and is dependent on its mass and velocity. Potential energy, on the other hand, refers to the energy that an object possesses due to its position or state, such as gravitational potential energy or elastic potential energy. Since the question mentions "energy in motion," it aligns with the concept of kinetic energy.
11.
Stored energy
Correct Answer
A. Potential
12.
Food has stored...
Correct Answer
C. Chemical energy
Explanation
Food has stored chemical energy because it is composed of molecules that contain energy-rich bonds. When we consume food, these bonds are broken down through digestion, releasing the stored energy in the form of ATP (adenosine triphosphate), which is used by our cells as a source of energy for various biological processes. This energy is then converted into other forms, such as mechanical energy for movement or thermal energy for maintaining body temperature. Therefore, the correct answer is chemical energy.
13.
Light waves traveling from the sun to Earth have...
Correct Answer
B. Kinetic energy
Explanation
Light waves traveling from the sun to Earth have kinetic energy. This is because kinetic energy refers to the energy of motion, and light waves are a form of electromagnetic radiation that travels in the form of waves. As light waves travel through space, they carry energy and momentum. This energy is transferred to objects upon absorption, causing them to heat up or generate electricity. Therefore, light waves possess kinetic energy as they propagate from the sun to Earth.
14.
A boulder sitting on the top of a hill has...
Correct Answer
A. Gravitational potential energy
Explanation
The boulder sitting on the top of a hill has gravitational potential energy. This is because it is at a higher position relative to the ground, and therefore has the potential to fall and convert its potential energy into kinetic energy as it moves downhill. Gravitational potential energy is the energy that an object possesses due to its position in a gravitational field.
15.
Energy cannot be created or destroyed, but it can be transformed.
Correct Answer
A. True
Explanation
This statement is a basic principle in physics known as the law of conservation of energy. It states that energy cannot be created or destroyed, but it can change from one form to another. This means that the total amount of energy in a closed system remains constant. Therefore, the given answer "true" is correct.
16.
A ball moving in a pinball machine has...
Correct Answer
B. Kinetic energy
Explanation
When a ball is moving in a pinball machine, it possesses kinetic energy. Kinetic energy is the energy associated with motion. As the ball moves, it has the ability to do work and transfer energy to other objects it collides with. Therefore, the correct answer is kinetic energy.
17.
A stretched rubber band has...
Correct Answer
A. Potential energy
Explanation
A stretched rubber band has potential energy because it is in a state of tension and has the ability to do work. When the rubber band is stretched, energy is stored in it, which can be released when the band is allowed to return to its original shape. This potential energy is a result of the elastic properties of the rubber band, which allows it to store and release energy.
18.
Heat transfer through a metal spoon is an example of ...
Correct Answer
A. Conduction
Explanation
Heat transfer through a metal spoon is an example of conduction. Conduction occurs when heat is transferred through direct contact between objects that are at different temperatures. In this case, the heat from the hotter object (such as hot soup) is transferred to the cooler object (the metal spoon) through direct contact. The metal spoon acts as a conductor, allowing the heat to flow from the soup to the handle of the spoon, making it hot as well. This process continues until the temperatures of both objects equalize.
19.
Correct Answer
B. Convection
20.
Correct Answer
C. Radiation
21.
What is the speed of a car moving 20 meters in 5 seconds?
Correct Answer
B. 4 m/s
Explanation
The speed of a car moving 20 meters in 5 seconds can be calculated by dividing the distance traveled by the time taken. Therefore, the speed is 20 meters divided by 5 seconds, which equals 4 meters per second.
22.
How much work is done if a man pushes a cart 2 meters with a force of 50 newtons?
Correct Answer
B. 100 J
Explanation
The work done is calculated by multiplying the force applied by the distance over which it is applied. In this case, the force is 50 newtons and the distance is 2 meters. Therefore, the work done is 50 newtons multiplied by 2 meters, which equals 100 joules (J).
23.
Correct Answer
B. Unbalanced