Physics Extra Credit
By: Grace Graber
Pictures of the Equations
If a car takes 20 seconds to travel from 20m to 84m, what the velocity of the car?
84 - 20 = 64m
64/20 = 3.2V = 3.2 m/s
If two cars are racing and Car A has 3 m/s and Car B has 4 m/s. How much time does it take for the cars to have acceleration of 8 m/s2?
8 = 4-3/t = 8 * t = 1/t * t
8t/8 = 1/8t = 0.125s
Velocity vs. Time Graphs
Velocity vs. time graphs of Accelerated Motion
The Velocity vs. Time Graph
If an object is accelerating, it is easier to work with the velocity vs. time graph than it is to work with the position vs. time graph. The velocity vs. time graph is the best tool for understanding acceleration. It clearly shows how the velocity of an object changes with time.
The slope of a velocity vs. time graph represents the acceleration of the object. Note that there is non-zero acceleration any time the velocity vs. time graph is not perfectly horizontal.
Calculating acceleration from the Velocity vs. Time Graph
The slope of a graph is equal to the ratio of rise to run. On the velocity vs. time graph, the rise and run have special meanings. The rise is the amount the velocity changes. The run is the amount the time changes.
Acceleration and Slope
Acceleration is the change in velocity over the change in time. This is exactly the same as the rise over run for the velocity vs. time graph. The slope of the velocity vs. time graph is equal to its acceleration.
Make a little Triangle to get the Slope
Displacement on an Accelerated-Motion Graph
Direction on Motion Graphs
Newton’s First Law of Motion
A push, pull, or other action that has the ability to change motion.
Forces, Mass, Inertia
Newton's First Law
Units of Force
The Net Force
Applications of Newton’s first law
- Seat belts and airbags
- Cup holders
- The tablecloth trick
Newton's Second law
Newton's Second Law
Acceleration = Force/Mass
Three Forms of the Second Law
- A = F/m - acceleration (a) - force (F) and mass (m)
- F = ma - force(F) - mass (m) and acceleration (a)
- M = F/a - mass (m) - force (F) and acceleration (a)