1.
Which of the following is a conversion from chemical energy to thermal energy?
Correct Answer
D. All of the above.
Explanation
All of the given options involve the burning of a substance, which is a chemical reaction that releases energy in the form of heat. When coal is burned at a power plant, gasoline is burned in a car engine, or charcoal is burned in a barbeque pit, chemical energy stored in these substances is converted into thermal energy, resulting in the production of heat. Therefore, all of the options mentioned involve the conversion of chemical energy to thermal energy.
2.
Which of the following is the best example of increasing an object's potential energy?
Correct Answer
C. Stretching a rubber band.
Explanation
Stretching a rubber band is the best example of increasing an object's potential energy because when a rubber band is stretched, work is done to store potential energy in the stretched rubber band. The potential energy is stored in the form of elastic potential energy, which is released when the rubber band returns to its original shape. This is different from the other options, as rolling a bowling ball, turning on a light bulb, and dropping a pencil do not involve the storage of potential energy in the same way as stretching a rubber band.
3.
An object that has kinetic energy must be...
Correct Answer
B. In motion
Explanation
An object that has kinetic energy must be in motion because kinetic energy is the energy possessed by an object due to its motion. Kinetic energy depends on the mass and velocity of the object. When an object is in motion, it has both mass and velocity, which allows it to possess kinetic energy. Therefore, if an object is not in motion, it does not have kinetic energy.
4.
Thermal energy is...
Correct Answer
A. Kinetic
Explanation
Thermal energy is the energy that comes from the movement of particles within a substance. It is directly related to the kinetic energy of the particles, as the higher their motion, the greater the thermal energy. Therefore, thermal energy is kinetic in nature.
5.
Sound energy is...
Correct Answer
C. The energy caused by an object's vibrations.
Explanation
Sound energy is the energy caused by an object's vibrations. When an object vibrates, it creates sound waves which carry energy. This energy is then transferred to our ears, allowing us to hear the sound. Sound energy can be produced by various objects, such as musical instruments, speakers, or even our vocal cords. It is a form of mechanical energy, as it involves the motion of particles in a medium (such as air, water, or solids) that transmit the sound waves.
6.
What device converts chemical energy to mechanical energy?
Correct Answer
D. All of the above.
Explanation
All of the above options convert chemical energy to mechanical energy. In the case of humans, the chemical energy from the food we consume is converted into mechanical energy to power our muscles and allow us to move. Similarly, in a car, the chemical energy in the fuel is converted into mechanical energy by the engine to propel the vehicle. Jet skis also convert chemical energy from fuel into mechanical energy to generate thrust and move through water. Therefore, all three options mentioned in the question convert chemical energy to mechanical energy.
7.
As height increases, so does...
Correct Answer
D. Potential energy.
Explanation
As height increases, the potential energy also increases. Potential energy is the energy possessed by an object due to its position or height above the ground. The higher an object is, the greater its potential energy. This is because when an object is lifted to a higher position, work is done against gravity, and this work is stored as potential energy. Therefore, as the height increases, so does the potential energy.
8.
The law of _________________ of energy states that energy cannot be created or destroyed.
Correct Answer
C. Conservation
Explanation
The law of conservation of energy states that energy cannot be created or destroyed. This means that the total amount of energy in a closed system remains constant over time. Energy can only be transferred or transformed from one form to another, but the total energy within the system remains unchanged. This principle is a fundamental concept in physics and is applicable to various phenomena, such as in the study of mechanical, thermal, and electromagnetic energy.
9.
According to the law of conservation of energy, in theory, a bouncy ball should never stop bouncing. However, we know that it eventually stops. Where does the energy go?
Correct Answer
C. Both A and B
Explanation
According to the law of conservation of energy, energy cannot be created or destroyed, only transferred or transformed. In the case of a bouncy ball, when it is dropped and bounces, some of the energy is converted into sound energy, causing the ball to make a sound as it hits the surface. This sound energy escapes into the surroundings. Additionally, some of the energy is converted into thermal energy due to the friction between the ball and the surface it bounces on. This thermal energy also escapes into the surroundings. Therefore, both options A and B are correct.
10.
Energy is...
Correct Answer
B. The ability to do work
Explanation
The correct answer is "Both A & B." This is because energy is the ability to do work, and when the surfaces of two objects rub against each other, they are doing work by transferring energy between them.