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2 years ago

What is the difference between chemical change and a physical change?

Physics

1 answer:

NeX [460]2 years ago

3 0

Answer:

Explanation:

There are several differences between a physical and chemical change in matter or substances. A physical change in a substance doesn't change what the substance is. In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed.

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1. Calculate the charge in a circuit which carries a current of 30 amperes for 5 seconds

sweet-ann [11.9K]

Answer:

1. 150C.

2. 50sec

3.1.5a

Explanation:

1. I = Q/T

Q= 30x5

=150c

2.applying the formulae, I = Q/T

T= Q/I

=500/10

=50sec.

3. using the formulae i=q/t

i= 120/80

=1.5a.

6 0

3 years ago

An object starts at rest. Its acceleration over 30 seconds is shown in the graph below:

ddd [48]

Answer:

The instantaneous speed of the object after the first five seconds is 12.5 m/s.

(C) is correct option.

Explanation:

Given that,

An object starts at rest. Its acceleration over 30 seconds.

We need to calculate the instantaneous speed of the object after the first five seconds

We know that,

Area under the acceleration -time graph gives speed.

According to figure,

$speed = area\ of\ tringle$

$speed=\dfrac{1}{2}\times b\times h$

$speed =\dfrac{1}{2}\times5\times5$

$speed-12.5\ m/s$

Hence, The instantaneous speed of the object after the first five seconds is 12.5 m/s.

6 0

3 years ago

Describe what happens to the system inside of a refrigerator or freezer in terms of heat transfer, work, and conservation of ene

Over [174]

Answer: A. Work is done on the system and heat is transferred from the system for a net decrease in internal energy.

Explanation:

A refrigerator is a device which dispenses heat from the close system to a warmer area or in the surrounding. By dispensing the heat the internal temperature of the refrigerator drops. The system of refrigerator violates the second law of thermodynamics. As it performs the work to cool the region instead of heating the region. The work is done on the system and the internal energy decreases and the heat energy is liberated to the surrounding area. A refrigerator is an open system.

6 0

2 years ago

Breathing on a cold window can cause it to fog up. which change of state causes this

Dominik [7]

When you breathe on a cold window and it fogs up, that change of state is called: Condensation.

Condensation is: The process in which molecules of a gas slow down, come together, and form a liquid water that collects as droplets on a cold surface when humid air is in contact with it.

I know this because I learned it in science class in school.

Hope I helped!

- Debbie

3 0

3 years ago

What is the benefit of developing the atomic mass unit as a standard unit of mass?

Alexeev081 [22]

Answer:

The atomic mass unit is 1/12 of an atom of carbon 12, and is a very small amount to represent in kilograms:

$1m_{u}=1.66054x10^{-27}kg$

$m_{u}$ is atomic mass unit.

This is why the benefits of the atomic mass unit is that it makes the representation of atomic masses easier in terms of the simplicity of the numbers that are used to represent the masses. Also using the atomic mass unit it is easier to compare the masses of different atoms, These numbers would be very small and would require negative powers of 10 to represent them, so it is more convenient to use the atomic mass unit.

3 0

2 years ago