Chapter 2: Describing Motion: Kinematics in One Dimension Flashcards
What is mechanics?
The study of motion of objects and the related concepts of force and energy.
What two parts is mechanics separated into?
Kinematics and Dynamics.
What is Kinematics?
The description of how objects move.
What is Dynamics?
Deals with force and why objects move as they do.
What is transitional motion? (which is the kind of motion this chapter deals with).
Objects that move without rotating.
In this chapter( and card set), what will we be concerned with the motion of?
Objects that move along a straight line path, also know as motion in one dimension.
We will often use the concept or model of an idealized particle which is what?
Considered to be a mathematical point with no spatial extent (no size).
A point partial can only undergo what type of motion?
Translation motion.
The particle model is useful when?
We are interested in translational motion only.
REFERANCE FRAMES AND DISPLACEMENT
REFERANCE FRAMES AND DISPLACEMENT
What is a reference frame or a frame of reference used for?
Any measurement of position, distance, or speed must be made in respect to a frame of reference.
While you are on a train traveling at 80 km/h, suppose a person walks to the front of a train at 5 km/h. What is his frame of reference?
This 5 km/h is the persons speed with respect to the train as a frame of reference.
With respect to the ground how fast is that person moving on that train?
80 km/h +5 km/h = 85 km/h.
When stating speed what is it always important to state
It is always important to specify the frame of reference.
Why do we have a reference frame really?
To avid confusion.
When specifying the motion of an object it is important to specify not only the speed but also what?
The direction of motion.
Often in physics how do we specify a direction?
Using north, east, south, and west, and by up and down.
In physics what do we usually draw as a frame of reference?
A coordinate system.
What do we place at the origin of the coordinate system?
0
In three dimensions what other axis is added to the coordinate system?
z.
What is displacement?
The change in position of an object; how far and object is from the starting point.
What are vectors?
Quantities that have both magnitude and direction.
To see the difference between displacement and distance imagine a person walking 70m to the east and then turning around and walking back west 30m, what is the distance the person traveled and what is the displacement?
The total distance traveled is 100 m, but the displacement is now only 40 m since the person is now only 40 meters from the starting point.
What are some examples of vector quantities?
Displacement,
What are vectors represented by in diagrams?
Arrows.
When will we deal with vectors more?
In chapter 3.
In one dimension motion; vectors that point in the opposite direction will do what?
Have a negative sign on the magnitude quantity.
SKILL 1: CALCULATING AVERAGE VELOCITY
What does the greek symbol delta (triangle) stand for?
A change in.
What does delta(x) mean?
A change in X.
Or a change in position which is displacment.
What does the “change in” any quantity mean?
The final value of that quantity minus the original of that quantity.
Whats the equation for displacment?
Delta(x) = x(2) - x(1)
is change in position which is displacment.
AVERAGE VELOCITY
AVERAGE VELOCITY
What is an importnat aspects of a moving object?
How fast an objcet is moving - its speed and velocity.
What does the term speed refer to?
How far an object travels in a given time interval, reguardeless of direction.
What is the definition of average speed?
The total distance travled along its path divided by the time it takes to travel this distance.
Whats the equation for average speed?
Distance traveled/time elapsed.
In physics does speed and velocity mean the same thing?
Why?
No;
Speed is just a positive number with a unit.
Velocity is used to signify both the magnitude (numerical value) of how fast an object is moving and also the direction in which it is moving.
Is velocity a scalar or a vector?
It has both magnitude and direction so it is a vector.
What is the second diffrence between speed and velocity?
The average velocity is defned in terms of displacemnt rather than total distance traveled.
When motion is in one dimension what does average speed and average velocity have in common?
They have the same magnitude, but in other cases may differ.
