MOTION AND FORCES
Motion is one of the key topics in physics. Everything in the universe moves. It might only be a small amount of movement and very slow, but movement does happen. Even if you appear to be standing still, the Earth is moving around the Sun, and the Sun is moving around our galaxy. The movement never stops.
The physics of motion is all about forces. Forces need to act upon an object to get it moving, or to change its motion. Changes in motion won't happen on their own.
Forces could be big, such as the pull of a star on a planet or very small, such as the pull of a nucleus on an electron. They are acting everywhere in the universe at all times. There are often many forces at work. Even if you were standing in one place, you would have many forces acting on you; for example, gravity.
If there is more than one force acting on an object, the forces can be added up if they act in the same direction, or subtracted if they act in opposition. Scientists measure forces in units called Newtons (N).
*Note: 1N = 1 kg x 1m/s2.
The net force applied to an object equals the mass of the object multiplied by the amount of its acceleration. Therefore, to calculate force, there is really only one formula to remember:
F = ma
F = the total (net) force (N)
m = the object's mass (kg)
a = the acceleration that occurs (m/s2)
To solve word problems, simply follow these three easy steps:
Step 1: Write down the formula needed to solve the problem
Step 2: Place the known measurements into the formula
Step 3: Enter the numbers into your calculator and solve
WORK
Another key part of physics is Work. Work is done when a force that is applied to an object moves that object. For example Sitting and looking at a computer screen is not work. Tapping on the keyboard and making the keys move is work. Basically, you have to exert a force AND move something to qualify as doing work.
Work is calculated by multiplying the force by the amount of movement of an object:
W = Fd
W = work (J)
F = force (N)
d = distance (m)
Here is an example of how to calculate work:
Q: How much work is done by a person who uses a force of 27.5N to move a grocery buggy 12.3m?
W = F x d
W=(27.5N) (12.3m)
W=338.25J
Motion is one of the key topics in physics. Everything in the universe moves. It might only be a small amount of movement and very slow, but movement does happen. Even if you appear to be standing still, the Earth is moving around the Sun, and the Sun is moving around our galaxy. The movement never stops.
The physics of motion is all about forces. Forces need to act upon an object to get it moving, or to change its motion. Changes in motion won't happen on their own.
Forces could be big, such as the pull of a star on a planet or very small, such as the pull of a nucleus on an electron. They are acting everywhere in the universe at all times. There are often many forces at work. Even if you were standing in one place, you would have many forces acting on you; for example, gravity.
If there is more than one force acting on an object, the forces can be added up if they act in the same direction, or subtracted if they act in opposition. Scientists measure forces in units called Newtons (N).
*Note: 1N = 1 kg x 1m/s2.
The net force applied to an object equals the mass of the object multiplied by the amount of its acceleration. Therefore, to calculate force, there is really only one formula to remember:
F = ma
F = the total (net) force (N)
m = the object's mass (kg)
a = the acceleration that occurs (m/s2)
To solve word problems, simply follow these three easy steps:
Step 1: Write down the formula needed to solve the problem
Step 2: Place the known measurements into the formula
Step 3: Enter the numbers into your calculator and solve
WORK
Another key part of physics is Work. Work is done when a force that is applied to an object moves that object. For example Sitting and looking at a computer screen is not work. Tapping on the keyboard and making the keys move is work. Basically, you have to exert a force AND move something to qualify as doing work.
Work is calculated by multiplying the force by the amount of movement of an object:
W = Fd
W = work (J)
F = force (N)
d = distance (m)
Here is an example of how to calculate work:
Q: How much work is done by a person who uses a force of 27.5N to move a grocery buggy 12.3m?
W = F x d
W=(27.5N) (12.3m)
W=338.25J