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# friction and gravity

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by

## Ian Ledbetter

on 5 November 2015

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#### Transcript of friction and gravity

by The Actual Blue Group
Experiment 2: Forced to Acceleration
One of our projects is called Forced to Acceleration. The project was used to see how much force is needed to get a skateboard to go 1 meter.
Gravity
Gravity is a force that pulls objects toward each other.
Acceleration
Acceleration, in everyday language, means "the process of speeding up." In scientific terms, acceleration is described as the rate in which velocity changes.
Calculating Speed
Friction
Materials used during this experiment
Skateboard
Ribbon
Books
Spring Scale
Data
Forces That Control Our World!
Friction is a force that two surfaces exert on each other when they rub together.
If you know the distance an object travels in a certain amount of time, you can calculate the speed of the object. To calculate the speed of an object divide the distance the object travels by the amount of time it takes to travel that distance.

Average speed
To calculate the average speed , divide the total distance traveled by the total time. If a cyclist travels 32 kilometers during two hours. Then travels 13 kilometers during the next hour. To find the average speed divide the total distance by the time.

Total Distance= 32km + 13m = 45km
Total Time= 2h + 1h =3h
Average Speed= 45km/ 3h = 15km/h
There are two factors effected by gravitational attraction: mass and distance.
Instantaneous speed
is the rate at which an object is moving at a given instant time.

Weight and mass
Weight is a body's relative mass or the quantity of matter contained. Mass is a measure of the amount of matter in an object.
Air Resistance and Free Fall
Air resistance, also called drag, is the force working in opposition to the relative motion of an object through the air.
Free fall is downward movement under the force of gravity only.
Calculating Acceleration
Acceleration equals velocity divided by time.
Speed
,
Time
and
Distance
S
T
D
Terminal Velocity
A
V
T
Decreasing Speed
Increasing Speed
Changing Speed
A=Acceleration

V=Velocity
T=Time
To determine the acceleration of an object moving in a straight line, you MUST calculate the change in speed per unit of time. This is summarized by the following formula:
Acceleration= Final Speed-Initial Speed
Whenever an object's speed increases, the object accelerates.
Time
For example: A softball accelerates when the pitcher throws it and again when the batter hits it.
Math Sample
As a roller coaster car starts down a slope, its speed is 4 m/s. 3 seconds later, at the bottom, its speed is 22 m/s. what is its average acceleration?
Initial S: 4
Final S: 22
Time: 3
22-4
3
=
18
3
=
6
the average acceleration is 6 m/s
2
Just as objects can speed up, they can also slow down. This change in speed is sometimes called deceleration, or negative acceleration.
Terminal velocity is the highest velocity attainable by an object as it falls through the air. It is called that because it is also the height at which a human will most certainly die.
For example: a softball decelerates when it lands in the fielder's mitt.

bibliography
the science text book
"EasyBib: The Free Automatic Bibliography Composer." <i>EasyBib</i>. N.p., n.d. Web. 04 Nov. 2015.
"Kahoot!" <i>Kahoot!</i> N.p., n.d. Web. 04 Nov. 2015.
SHOE
A
B
trial 1
trial 2
Data table
trial 3
Even an object that is traveling at a constant speed can be accelerating. Recall that acceleration can be a change in direction as well as a change in speed. Therefore, a car accelerates as it follows a gentle curve in the road or changes lanes.
3 1/2 (n)
3 (n)
4 (n)
2 1/2 (n)
2 1/2 (n)
3.7 (n)
Static friction is two or more solid objects that are not moving relative to each other.
Sliding friction is the resistance of 2 objects sliding against each other.
The Causes of Friction

The strength of the force of friction depends on two factors:

How hard the surfaces push together
The types of surfaces involved

Rolling friction is the force resisting on a round object when it is rolling.
Fluid Friction is when a solid object moves through a liquid.