Unit One Summary Blog Post- 9/26
Part A- What I Learned
In the first unit of the year, we covered 4 main topics: Newton’s First Law, Velocity, Acceleration, and Net Force and Equilibrium. Each topic built off of the other topics, increasing our comprehension of the subjects.
Newton’s First Law states clearly:
“An object in rest tends to stay at rest, while an object in motion tends to stay in motion, unless an unbalanced force acts upon it.”
Tablecloth example:
The dishes stayed on the table because the force (pulling) was on the tablecloth, not on the dishes themselves. A perfect example of Newton’s First Law, the dishes remained at rest as there was no force acting upon them.
Velocity
Velocity is measured in meters per second, or m/s.
Like speed, Velocity measures distance over time, or d/t. However, unlike speed, velocity requires a specific direction. CONSTANT VELOCITY requires no change in direction. This is perhaps best understood through an example of a race car on a track. A car has speed while on the track, however since it is constantly making changes in direction, it is unable to have constant velocity.
As a result of the curves in the racetrack, race cars do not travel with constant velocity.
There are two formulas used to measure velocity. To answer the question “How Far?” the equation d=vt is used.
For example: If an albino alligator is traveling at a constant velocity of 15m/s, how far will it travel in 10 seconds?
d=vt
d=(15m/s)(10)
d=150m
The second formula that is used to measure velocity answers the question “How Fast?” v=d/t
For example: If an armadillo travels 100 meters in 25 seconds, how fast is it going?
v=d/t
v=100/25
v=4m/s
Velocity can be changed in three ways: by speeding up, by slowing down, and by changing direction. As soon as any one of these three things occur, Constant Velocity is impossible.
Acceleration
Acceleration is the change in speed, both increasing and decreasing. The units used to measure acceleration are m/s².
To find Acceleration, the equation “acceleration=change in velocity/time” is used. This can also be written as “a=△v/t”
Acceleration is well explained through examples of ramps with varying steepness:
If a ball was placed on the ramp, it would begin at 0m/s². As it rolled down the ramp, the acceleration would change from 0m/s² to 2m/s², then to 4m/s², then 6m/s², and so on. Because the change from one acceleration rate to another is 2, the acceleration of the ball would be 2m/s².
When a ball is dropped straight down and is not affected by any drift of air, it is ALWAYS accelerating at a rate of 10m/s².
There are also two equations used to find acceleration. To answer the question “How Far?”, d=1/2at² is used.
For example: If a emu is traveling at a constant acceleration of 16 m/s², how far will it travel in 10 seconds?
d=1/2at²
d=1/2(16m/s²)(10²)
d=1/2(16)(100)
d=1/2(1600)
d=800m
To answer “How Fast” for acceleration, v=at is used.
Another example: If a badger started at rest and began accelerating at a constant 5m/s², how fast would it be going after 20 seconds?
v=at
v=(5m/s²)(20)
v=100 m/s
Any time that the acceleration of an object is changing, (increasing OR decreasing), the velocity of that object is Increasing. However, if the acceleration is constant, the velocity is also Constant.
Net Force and Equilibrium
Newtons (N) are used to measure Force (a push or a pull). Approximately 1/4 of a pound is equal to 1 N. NET FORCE is the total force on an object. Any time that the net force is anything other than zero, the object is accelerating.
If 5N of force are being pushed from the top arrow on to the box and 5N are being pushed on to the box from the bottom arrow, the Net Force on the box would be (5N)+(5N), or 10N.
Equilibrium occurs when the Net Force is equal to 0N.
If 6N are being pushed by the arrow on the right
and 6N are being pushed by the arrow on the left, the Net Force is (6N)-(6N), or 0N.
Equilibrium occurs in to instances: when an object is at rest or when it is moving at constant velocity.
*MASS is a measure of inertia, while WEIGHT is the force with which the Earth pulls on any given object.
Connections Made
Although it is a simple connection, solving with variables, such as d=vt, etc., helped me extensively with understanding these concepts, specifically Velocity and Acceleration. My simple Algebra I problem solving skills made both the answering of the questions as well as understanding how the graphs come into play.
Velocity Podcast
