What are Newton's Laws of Motion?
Isaac Newton was an English physicist and mathematician. His Laws of Motion introduce us to physics. Physics is the study of how matter behaves and moves. Matter is physical substance. It is anything that has mass and takes up space.
These laws show us how objects behave when they are standing still and when they are moving. They describe what happens to objects when forces act on them. There are three Laws of Motion. Here is a description of them.
Newton's First Law Of Motion
Newton's First Law of Motion says that an object in motion tends to stay in motion. This stops being true when a force acts on the object. The force could slow it down, stop it or change its direction. The law also applies to objects at rest. This means that they are not moving. If an object is at rest, it tends to remain at rest. This stops being true if a force acts on it. The force would move it. This law is also known as the Law of Inertia. In science, inertia refers to how matter tends to keep doing what it's doing.
Basically, what Newton's First Law is saying is that objects behave predictably. If a ball is sitting on your table, is it going to start rolling around or bouncing? It won't unless a force acts on it to cause it to do so. In the same way, moving objects don't change their direction. Not on their own, at least. They only change direction if a force causes them to move from their path. For example, a rolling ball won't change direction on its own. But it will change direction if a force acts on it. The force could be your foot kicking the ball.
As you know, if you slide a block across a table, it eventually stops. It doesn't slide along forever. This is because of the force of friction. Friction opposes the block's movement. If you throw a ball on Earth, gravity and air friction will cause the ball to stop at some point. If, however, you threw a ball out in space, the ball would just keep going. This is because there is much less resistance in space.
Newton's Second Law Of Motion
Newton's Second Law of Motion describes what happens when a force acts on an object. The force will cause the object to accelerate. In science, accelerate refers to the rate of change in speed. How much force is needed to cause an object to accelerate? It depends on the mass of the object. The larger the object's mass, the greater the force needed to cause it to accelerate. This law may be written as force = mass x acceleration, or:
F = m * a
Remember, this is not about an object's weight. Weight is not mass. Mass is how much matter is in an object. Weight has to do with the force of Earth's gravity on an object's mass. It might take more force to move a heavy object than to move a light object. Mass is responsible for this.
Newton's Second Law of Motion also explains deceleration, or slowing down. You can think of deceleration as acceleration with a negative sign on it. For example, a ball rolling down a hill moves faster as it keeps rolling. It accelerates as gravity acts on it in the same direction as the motion. Acceleration is positive. If a ball is rolled up a hill, the force of gravity acts on it in the opposite direction of the motion. So, acceleration is negative, or the ball decelerates. This means that it moves slower as it continues up the hill.
Newton's Third Law Of Motion
Newton's Third Law of Motion says that for every action, there is an equal and opposite reaction. Forces always come in pairs. They tend to balance each other.
What this means is that when you push on an object, that object pushes back. It's doing the same amount of pushing but in the opposite direction. For example, when you are standing on the ground, you are pushing down on the Earth. At the same time, it is pushing back up at you. It is doing so with the same force. Imagine you're in a swimming pool with fins on. You kick your legs, and you push water away from you. But the water pushes back with the same force and you move forward.
History Of Newton's Laws Of Motion
Sir Isaac Newton introduced the three Laws of Motion in 1687. They were explained in his book "The Principia." The same book also discussed the theory of gravity. His book described many of the main rules of physics. These rules are still used today.
The main idea of the article is that Newton's Three Laws of Motion teach us important rules about physics.
Which key detail supports the main idea?
A
Isaac Newton was an English physicist and mathematician.
B
Physics is the study of how matter behaves and moves.
C
It is anything that has mass and takes up space.
D
They describe what happens to objects when forces act on them.
How does the information in the section “History Of Newton's Laws Of Motion” support the main idea of the article?
A
It explains who came up with the three Laws of Motion and what each of them states.
B
It explains who came up with the three Laws of Motion and where they were first described.
C
It shows when the three Laws of Motion were written and how they are different from other physics laws.
D
It shows when the three Laws of Motion were written and how they have changed over time.
Read the selection from the section "Newton's First Law Of Motion."
Basically, what Newton's First Law is saying is that objects behave predictably. If a ball is sitting on your table, is it going to start rolling around or bouncing? It won't unless a force acts on it to cause it to do so. In the same way, moving objects don't change their direction.
What does the author mean by "predictably"?
A
in an interesting way
B
in a surprising way
C
in an expected way
D
in a dangerous way
Read the selection from the section “Newton's Second Law Of Motion."
You can think of deceleration as acceleration with a negative sign on it. For example, a ball rolling down a hill moves faster as it keeps rolling. It accelerates as gravity acts on it in the same direction as the motion. Acceleration is positive. If a ball is rolled up a hill, the force of gravity acts on it in the opposite direction of the motion. So, acceleration is negative, or the ball decelerates. This means that it moves slower as it continues up the hill.
Which phrase from the selection helps the reader understand the meaning of "deceleration"?
A
keeps rolling
B
same direction
C
moves slower
D
continues up
my answers are B, A, C, C
A. Isaac Newton was an English physicist and mathematician.
B. It explains who came up with the three Laws of Motion and where they were first described.
C. in an expected way
C. moves slower
B
The key detail that supports the main idea is D - They describe what happens to objects when forces act on them. This detail supports the main idea because it directly relates to Newton's Laws of Motion, which describe the behavior of objects when forces are applied to them.
The information in the section "History Of Newton's Laws Of Motion" supports the main idea of the article by explaining who came up with the three Laws of Motion (Isaac Newton) and where they were first described (in his book "The Principia"). Therefore, B - It explains who came up with the three Laws of Motion and where they were first described is the correct answer.
When the author uses the term "predictably" in the section "Newton's First Law of Motion," they mean that objects behave in an expected way. This is indicated by the statement that objects won't start rolling or bouncing on their own unless a force acts on them. Therefore, the correct answer is C - in an expected way.
The phrase from the section "Newton's Second Law of Motion" that helps the reader understand the meaning of "deceleration" is "moves slower." This phrase indicates the opposite of acceleration, which means that the object is slowing down. Therefore, the correct answer is C - moves slower.