Every object continues in a state of rest or of uniform speed in a strait line unless acted on by a nonzero net force.
Another way to say this is that an object at motion with stay in motion and an object at rest will stay at rest unless acted on by an outside force. The prime example of this law is where someone has set up a dinner ware set and pulls the table cloth out from underneath it. The dishes stay in their restful state because their inertia is greater than the force acted on it.
This same concept applies to objects in motion. An object at motion with continue to move without turning or gaining speed. This was the concept demonstrated by our hovercraft lab. Although, this concept is mainly evident in space, we were able to recreate a friction-less environment by keeping the craft floating above the ground.
This video demonstrates that when she has to get stopped and started by on outside force. Before she is pushed she is at rest, after she is pushed she reaches constant velocity. This also can be defined as equilibrium.
Mass is also directly related to inertia. Mass is the coherent measure of how much matter somebody or something consists of. This is equally applied to inertia. The more mass a person has the more inertia they have. meaning it is harder to create that initial start and stop when being pushed on the craft.
Net force is where more than a single force acts on an object at one time. When two forces are acting on an object at once in opposite directions that are equal, the net force is 0N.
When one of those forces has an unequal amount of force then you simply subtract those two to find what the net force is. For example, if you and a friend pull on a box in opposite directions, and you are pulling at a force of 50N of force and your friend is pulling at 100N of force. The way to calculate that would be to take 100-50 to find that the net force equals 50N. However, there doesn't necessarily need to be an opposing force acting on the object to calculate its net force. If you push an object at force of 100 newtons and it moves then the net force on the object is 100N. This is because the force acting on the object is greater than the friction acting as the resisistance.
As we move into Chapter 3 we are introduced to the properties of linear motion. Speed is the distance covered per unit of time, or Speed = distance/time.
This same concept is applied when trying to calculate the average speed of an object. The formula for that is Average speed = total distance covered/time interval
The difference between velocity and speed is that velocity shows the direction an object is moving in. If a car is moving around a track at 6m/s it is traveling at a constant speed but it is changing direction so the velocity changes. This proves that it is possible to have a constant speed but changing velocity, but not possible to have constant velocity but changing speed.
It is possible to change the velocity of something because of its changing speed, and direction or both speed and direction. We can calculate acceleration by how quickly an object's velocity changes.
Acceleration = change of velocity/ time interval
For example, we can relate this to how the change in someones velocity is defined as acceleration. If someone is accelerating then they are rapidly gaining speed or slowing down, but they are not traveling at a constant velocity.
Acceleration can be constant or increasing depending on the force that is acted on it. The book demonstrates 3 ramps that a ball is rolling down. All have increasing acceleration to a point, but some remain constant and others keep increasing.
The way to calculate increasing acceleration is multiply the acceleration over a time interval.
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