Be able to identify numbers which are:

• Vector - has a quantity and direction;  Example: velocity, acceleration
• Scalar - only has a quantity;  Ex: mass, volume, time
• This distinction is important because vectors don't always add together like scalar.  You will see this later when we discuss force and energy.

• Displacement - the distance between an object's starting and stopping position
• Distance traveled - the distance of the actual path traveled by an object
• [Drawing a picture is very helpful!!!]

Velocity is the speed of an object.
Velocity = distance ÷ time v = x ÷ t v = x/t
Where  v = velocity  x = distance traveled t = time

Velocity units are length/time (Ex: mm/seconds, mile/hour km/seconds, meters/minutes)

Sample Test Question:  A car travels 100 kilometers in 50 minutes.  What is it's average velocity?
Average velocity = total distance / total time
                 = 100 km / 50 min
                 = 2 km/min
                Answer:  avg. vel. = 2 km/min

Be able to explain the behavior of a displacement versus time graph.

• The slope of a straight line can be used to find average velocity.
• A straight line indicates uniform (unchanging) velocity.
• A curved line indicated increasing velocity (acceleration).
• You will not need to calculate the slope of a line.

Acceleration - an increase in an objects velocity; speeding up
Deceleration - a decrease in an objects velocity; slowing down
Free fall - the action of an object that is falling toward the ground with nothing to slow it down
Vacuum - a volume with no air or atmosphere.
wind resistance - the force of air molecules which causes objects to slow down
air friction - the force of air molecules which causes objects to slow down
terminal velocity - the maximum speed an object can fall in our atmosphere;  the limiting speed is caused by wind resistance and air friction; the more surface area an object has, the slower it's terminal velocity
 
 

An object's free fall acceleration is affected by it's surface area.  Basically, a smaller surface area allows an object to pass through the air more easily.  [Ex. A 1 gm and a 10000 gm object free fall at the same acceleration and velocity if their surface area are the same.]
 

Pendulum - a mass on a string that can oscillate back and forth
[Be prepared to draw a pendulum and describe how and why we used it in the motion lab.]

Viscosity -the thickness of a liquid; vegetable oil is more viscous than water
[When given 2 sample liquids, you may be asked to determine which liquid is more viscous.]