Download Newton`s 2nd Law of Motion:

After carefully reading the information on the back, explain each of the
underlined terms in your own words. Do NOT copy the definitions from
the back!
1. Mass: __________________________________________________
2. Weight: ________________________________________________
3. Speed: _________________________________________________
4. Velocity: _______________________________________________
5. Acceleration: ____________________________________________
6. Newton’s 2nd Law: ________________________________________
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Answer the following questions.
7. Write the equation for Newton's second law three different ways.
8. Why is it sometimes useful to write this law in different ways? _______
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9. Why do people often confuse mass and weight? ___________________
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Newton’s 2nd Law of Motion:
Force, Mass, and Acceleration
Mass is a measure of the amount of matter in an object. The amount of inertia an object
has depends on its mass. The greater the mass of an object, the greater its inertia. Mass,
then, can also be defined as a measure of the inertia of an object. Mass and weight are
closely related but do not mean the same. Weight is a measure of the force of gravity on
an object. When you weight yourself, you are actually measuring how much the earth’s
gravity is pulling down on your mass.
The speed of an object tells you how fast that object is moving (example 55 miles per
hour). Speed and velocity are closely related but not the same. Velocity is speed in a given
direction (example: 55 miles per hour going north). So, velocity has two components –
speed and direction. Any time there’s a change in velocity, acceleration is present.
Acceleration describes the rate at which velocity changes. Acceleration involves a change
in either speed or direction. In science, acceleration refers to increasing speed, decreasing
speed, or changing direction. Any time the speed of an object changes, the object
experiences acceleration. An object that is changing direction is also accelerating, even if
it is moving at a constant speed. The moon accelerates because it is continuously
changing directions as it revolves around Earth.
Newton’s second law of motion explains that the force of an object equals its mass times its
acceleration. This law shows how force, mass, and acceleration are related. In other
words, the net force on an object is equal to the product of its acceleration and its mass.
The relation among force, mass, and acceleration can be written in one equation that is
referred to as Newton’s second law of motion. According to his 2nd law, Force = Mass x
Acceleration.
In the above equation, you can see that the value for force (F) will increase if the value for
acceleration (A) increases. Force and acceleration change in the same way because both
get larger or smaller together. The equation also means that the value for acceleration
also will increase if the value for mass (M) decreases. Mass and acceleration change in
opposite ways. The relationship between force, acceleration, and mass can be shown in
the following ways:
F = M x A (Newton’s 2nd Law)
If A
, then F
If A
, then F
If M
, then F
If M
, then F
If M
, then A
If M
, then A