Relative Density of Substances and Specific Gravity

A natural force that pulls a body towards the center of the earth is termed _____.

• A. Centripetal force

• B. Centrifugal force

• C. Black hole

• D. Average acceleration

• E. Gravity

• F. Momentum

A Greek letter that expresses density is _____.

• A. Alpha_d

• B. Beta_d

• C. Theta_d

• D. rho

• E. dho

• F. dhr

A glass of water has a higher density than an exact glass of oil.

• A. True

• B. False

An 🍎 apple 🍎 falling from a tree has an unbalanced force.

• A. True

• B. False

Force is a quantity measured in _____.

• A. Kilogram

• B. Gravity

• C. Incandescence

• D. Meter per second square (ms^-1)

• E. Mole

• F. Newton

Heat transfer indicates two systems of varying temperatures and will always be transferred from a region with lower temperature to another with higher temperature.

• A. True

• B. False

Heat can be created.

• A. True

• B. False

Temperature is defined as the measure or ability of an object or substance to transfer heat energy to another object or substance.

• A. True

• B. False

One quarter of an apple is filled with air and that's why they float in water

The Nobel price was named after its founder, Alfred Noble. He is a Swedish, born on October 21, 1833; and was the inventor of dynamite. He was also a a famous scientist and a successful business man.

Glass balls bounce higher than rubber balls

Every planet has its own unique gravitational force. For instance, Mars has a gravity of 3.711 m/s² while earth’s gravitational force is 9.807m/s².

When two metals are put together in space, they will stick together as if they are welded. This phenomenon is called cold welding

The fastest animal on land is cheetah. It can reach a maximum speed of about 113km per hour.

The earth is governed by the force of gravity and that’s why everything present on it (humans, plants, animals and even air) is always drawn towards it. You will actually need some form of force greater than gravity in order to pull yourself away from the earth.

As an instance, the earth as we know is spherical in shape and held in space. Also, all humans live on a constantly rotating earth and not inside the earth. Since we live on a spherical earth held in space, how come humans are yet to fall off the constantly rotating earth?

Well, the answer is gravity. Even if we attempt to jump off the earth into space, the force of gravity present on earth will still pull us down. In fact, in order to leave the earth; there has to be a force stronger that gravity; which must be applied to whatever is attempting to leave the earth. For this reason:

Whenever one jumps, a certain amount of force is needed to be applied by that person. However, gravity still return the person back to earth because the applied force had been exhausted.

Please read more on the concept of gravity here.

The larger the size of an object, the greater it’s force of gravity. Gravity is therefore affected by the size and closeness of objects.

Since the earth is larger than the moon, it will have a greater gravitational force than the moon. We will be more attracted on the earth than we would on the moon if we were astronauts on the moon. This implies that we will weigh differently on both places. For this reason, our weight will also vary on the various planets (because they are of different sizes). This is shown in the diagram below:

Weight depends on the degree at which the gravity on earth or moon or another planet pulls an object while the Mass of any object or body will always remain the same (constant) since it’s the amount or quantity of matter in the body.

Please read on mass versus weight here

To better understand the Zeroth Law of Thermodynamics, we need to know what thermal equilibrium is. This is explained below:

Two bodies A and B are said to be in thermal equilibrium if each body can transfer heat to each other when placed closed together but ended up not transferring any heat to each other.

This will mean that both bodies are at equal temperature.

Now, according to the zeroth law, assuming we have three bodies namely X, Y and Z:

If X = Y and Z = Y, then X = Z

From the above expression, it will be observed that: if X and Y are in thermal equilibrium and Z and Y are in thermal equilibrium, therefore, X and Z must be in thermal equilibrium too.

So we can see that according to the zeroth law, temperature is a quantity worth measuring.

It can therefore be said that temperature is the quantity that remains constant (the same) for all systems in thermal equilibrium.

Consequently, the zeroth law of Thermodynamics states that if two separate bodies are in thermal equilibrium with another body, then they are also in equilibrium with each other

Please read more on the zeroth law of thermodynamics here

Fundamental units are the units of fundamental quantities.

A fundamental unit is a unit that does not depend on any other unit; neither can it be changed nor is related to another fundamental unit.

A fundamental unit is also referred to as a basic unit.

Fundamental Units are always constant. This means that they don't change, (remains the same) and are standardized all over the world.

The fundamental quantities alongside their respective fundamental units are 7 in number. They include:

1. Mass (m) is a fundamental quantity whose unit is kilogram (kg)

2. Length (l) is a fundamental quantity whose unit is meter, (m)

3. Time (t) is a fundamental quantity whose unit is second (s)

4. Temperature (T) is a fundamental quantity whose unit is Kelvin (k)
   You can read on the Concept of Temperature and Heat here.

5. Electric Current (I) is a fundamental quantity whose unit is ampere (A)

6. Amount of Substance (n) is a fundamental quantity whose unit is mole (mol)

7. Luminous Intensity (|^v) is a fundamental quantity whose unit is candela (cd)

Please read more on fundamental units here

The classical mechanics (laws of motion) is a fundamental part of Physics.

Below are the Newton's laws of motion:

An object at rest will continue in its state of rest; while an object in uniform motion will continue in a straight line, unless an external force acts on it.

Newton's first law of motion.

Please read on motion and speed here.

The rate of change of momemtum is proportional to the applied force and will take place in the direction of that force.

Newton's second law of motion.

To every action, there is an equal and opposite reaction.

Newton's third law of motion.

Please read on Newton's laws of motion here.