How much nuclear energy do you need to toast a piece of bread?

12) Conduction. In fact, in conduction the heat is transferred when molecules collide with each other.

13) This is called thermal equilibrium. When we put two objects with different temperature in contact, their molecules have different kinetic energies. The molecules of the object with higher temperature are more energetic, and therefore they start to transfer part of their energy (by collisions) to the molecules of the object with lower temperature, until they reach a condition of equilibrium (i.e. the kinetic energies of the molecules of the two objects will be the same), and this happens when the two objects have same temperature.

14) Convection. Convection takes place in fluids: the heat is transferred by the movement of masses of fluids, from warmer regions to cooler regions.

15) Figure is missing.

16) Mechanical->Electrical. In fact, by walking through the room (movement, so mechanical energy) the body of the person acquired more electrostatic charges, and when it touches the doorknob a spark (electrical energy) takes place, because the charges accumulated on the body find a way to reach the ground throught the doorknob.

17) Law of Conservation of Energy. Indeed, it says that energy can convert into different forms, but the total energy of an isolated system must be conserved.

18) Electrical. In the cathode-ray-tube televisions, for instance, the image on the screen is produced by a current of electrons hitting the screen.

19) The chemical energy in the food is converted to mechanical energy to give the body energy to move. The energy for our body is in fact produced by the chemical reaction of the molecules of the food, and then it is used by our body to move, for instance.

20) Convection. Most of the heater uses water, which is heated and then it starts its flow to distribute the heat, therefore by convection.

21) Figure is missing.

22) The temperature of the steel decreases and the temperature of the water increases. In fact, as we said in number 13), the steel will transfer part of its energy to the water until they reach thermal equilibrium, so the temperature of the steel will decrease while the temperature of the water will increase.

23) It is given off as other forms of energy. In particular, it is converted into radiant energy: the bulb emits light, which is electromagnetic radiation, so the energy is re-emitted as radiation.

24) When two objects collide. For instance, assuming there is a body moving with speed v and another body stationary (with same mass), when they collide the first body transfers its kinetic energy to the second body, putting it in motion.

25) Electrical -> thermal. In a toaster, there is a resistance through which current flows. Due to the Joule effect, the current flowing through the resistor causes an increase of temperature of the resistor itself, therefore the energy of the current (electrical) is converted into thermal energy, which is then used to heat the toast.

12) Conduction. In fact, in conduction the heat is transferred when molecules collide with each other.

13) This is called thermal equilibrium. When we put two objects with different temperature in contact, their molecules have different kinetic energies. The molecules of the object with higher temperature are more energetic, and therefore they start to transfer part of their energy (by collisions) to the molecules of the object with lower temperature, until they reach a condition of equilibrium (i.e. the kinetic energies of the molecules of the two objects will be the same), and this happens when the two objects have same temperature.

14) Convection. Convection takes place in fluids: the heat is transferred by the movement of masses of fluids, from warmer regions to cooler regions.

15) Figure is missing.

16) Mechanical->Electrical. In fact, by walking through the room (movement, so mechanical energy) the body of the person acquired more electrostatic charges, and when it touches the doorknob a spark (electrical energy) takes place, because the charges accumulated on the body find a way to reach the ground throught the doorknob.

17) Law of Conservation of Energy. Indeed, it says that energy can convert into different forms, but the total energy of an isolated system must be conserved.

18) Electrical. In the cathode-ray-tube televisions, for instance, the image on the screen is produced by a current of electrons hitting the screen.

19) The chemical energy in the food is converted to mechanical energy to give the body energy to move. The energy for our body is in fact produced by the chemical reaction of the molecules of the food, and then it is used by our body to move, for instance.

20) Convection. Most of the heater uses water, which is heated and then it starts its flow to distribute the heat, therefore by convection.

21) Figure is missing.

22) The temperature of the steel decreases and the temperature of the water increases. In fact, as we said in number 13), the steel will transfer part of its energy to the water until they reach thermal equilibrium, so the temperature of the steel will decrease while the temperature of the water will increase.

23) It is given off as other forms of energy. In particular, it is converted into radiant energy: the bulb emits light, which is electromagnetic radiation, so the energy is re-emitted as radiation.

24) When two objects collide. For instance, assuming there is a body moving with speed v and another body stationary (with same mass), when they collide the first body transfers its kinetic energy to the second body, putting it in motion.

25) Electrical -> thermal. In a toaster, there is a resistance through which current flows. Due to the Joule effect, the current flowing through the resistor causes an increase of temperature of the resistor itself, therefore the energy of the current (electrical) is converted into thermal energy, which is then used to heat the toast.

1. B
2. D
3. C
4. C
5. C
6. A
7. B

1. B
2. D
3. C
4. C
5. C
6. A
7. B

I hope its help for you

have a great day

I hope its help for you

have a great day

The electric energy converted in a toaster is A thermal and light

The electric energy converted in a toaster is A thermal and light

Question no. 1:

Controlled experiment is an experiment which is designed to test a variable, which can be changed during the experiment.

Explanation:

Hence in this experiment, the importance of experiment is being tested, as it is added only in one set of plant.

A manipulated variable is an independent variable whose amount can be changed during an experiment.

Here the fertilizer is a manipulated variable.

Question 2:

Because theory is the most organised statement proved by a set of independent experiments.

Explanation:

Hypothesis is the initial idea on which basis different experiments are conducted. But if 1 experiment succeeded and it supports the hypothesis, hypothesis do not become a theory.

For a theory, different experiments are necessary which supports that hypothesis.

Question no 4.

Density = 1.909 kg/m3

Explanation:

Given data:

Mass of the object = 42 kg

Volume of the object = 22 m3

Density of the object = ?

Solution

Density = mass/volume

Density =42/22 = 1.909

Density = 1.909 kg/m3

Hence the density of the object is 1.909 and its unit is kg/m3 which is system international unit of density.

Question 5.

Chlorine and water in swimming pool are mixed in such a way that there composition remains same throughout the mixture. And chlorine cannot be separated back from water. This is the homogeneous mixture.

Explanation: A homogeneous mixture is a mixture of more than one substance which are mixed together in such a way that they cannot be separated and the composition of the mixture remains same throughout the mixture. Example of homogeneous solution is sugar solution in water. As for swimming pool cleaning chlorine is added in pool water, it mixes in the whole water by diffusion. Hence it is a homogeneous mixture. Question no. 6.

Because physical change does not include composition change, it includes change in physical parameters. And in splicing tomato only change in shape is done.

Explanation: Chemical change means irreversible chemical composition change like the burning of toast. Physical change means reversible or irreversible change in shape, volume density without change in chemical composition. Splicing tomato comes under 2nd category because it does not include chemical change.

Remaining questions are attached in the files.