What is a motion diagram?
A series of images showing the positions of a moving object at equal time intervals
Particle Model
A simplified version of a motion diagram in which the object in motion is replaced by a series of single points. In order to use this model, the size of the object must be much less than the distance it moves.
Coordinate system
Tells you the location of the zero point of the variable you are studying and the direction in which the values of the variable increase.
Origin
The point where both variables are zero.
Vectors
Quantities that have both size (magnitude) and a direction
Scalars
Quantities that are just numbers without any direction, such as distance, time, or temperature. (opposite of vectors)
Resultant
The vector that represents the sum of the other two vectors. The resultant always points from the tail of the first vector to the tip of the last vector.
Displacement
Change in position
Average velocity
The slope of a position vs. time graph, which is represented by the ratio of the change of position to the time interval during which the change occurred.
Average speed
The absolute value of the slope of a position vs. time graph. It tells you how fast the object is moving. The sign of the slope tells you in what direction the object is moving, which makes it a vector with velocity.
What is the difference between speed and velocity?
Velocity contains information about the direction of motion while speed does not
The quantity of 2.67e3 has how many significant figures?
3
If Sam walks 100m to the right, then 200m to the left, his net displacement vector points...?
To the left!
Velocity vectors point ______ in relation to displacement vectors?
In the same direction as displacement vectors
4 types of motion we will study
- Straight line motion
- Circular motion
- Projectile motion
- Rotational motion
Maria is at position x=23m. She then undergoes a displacement of -50m. What is her final position?
-27m
Motion at a constant speed is called ____?
Uniforma motion
Significant figures
Digits that are reliably known
Displacement vector
Starts at the object's initial position and ends at its final position.
What is the slope at a point on a position vs. time graph of an object?
The object's instantaneous velocity at that point
What is the area under a velocity vs. time graph of an object?
The displacement of the object
How do you know from a position vs. time graph if an object's motion is uniform?
The graph is a straight line
Instantaneous velocity
An object's velocity at a specific instant in time
A 1-lb. ball and a 100-lb ball are dropped from a height of 10 feet at the same time. In the absence of air resistance...?
The two balls hit the ground at the same time
Acceleration
The rate of change of velocity, and the slope of a velocity vs. time graph
Quadratic relationships
Two quantities are said to have a quadratic relationship if y is proportional to the square of x.
Which objects are in freefall?
Any object moving under the influence of gravity only and no other forces.
Which direction does the freefall acceleration point?
It always points down, no matter what direction the object is moving
What is the freefall acceleration value?
9.80 m/s/s, vertically downward
A(x) is the _____ of the vector A
x-component
Coordinate systems
Artificially imposed grids you place on problems
The acceleration vector of a particle in projectile motion....?
Is directed down at all times!
Projectile motion
A projectile is an object that moves in two dimensions under the influence of gravity and nothing else. It follows a trajectory with the mathematical form of a parabola.
In projectile motion, the horizontal motion is constant and the vertical motion is fr
Uniform circular motion
Constant speed but constantly changing direction
Period
Time interval for an object to complete one revolution
Frequency
The number of revolutions per second (f=1/period)
Is there any acceleration in circular motion?
There is always an acceleration because the velocity is always changing direction.
What is velocity in circular motion?
Tangent to the circular path!
Where does acceleration point in circular motion?
Toward the center of the circle
Net force
The vector sum of all the forces acting on an object
If you are standing on the floor, motionless, what are the forces that act on you?
Weight force and normal force
Newton's First Law
The Law of Inertia. If an object has no force acting on it, it will continue to remain at rest or move in a straight line at a constant speed until another force interferes.
What are the types of forces?
Weight
Spring force
Tension force
Normal force
Friction
Drag
Thrust
Electric and Magnetic forces
What are the 3 types of friction?
Static friction
Kinetic friction
Rolling friction
Drag force
Air resistance. It points opposite to the direction of motion.
Thrust force
Is exerted on a rocket by exhaust gases
Free-body diagrams
Diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation. The size of the arrow in a free-body diagram reflects the magnitude of the force, and the direction of the arrow shows the direction that
Static equilibrium
When an object remains at rest, it is in static equilibrium and has 0 acceleration
Dynamic equilibrium
When an object moves in a straight line at a constant speed, it is in dynamic equilibrium and has 0 acceleration
When looking at drag, going twice as fast requires...?
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