Transcript Reveiw PPT 2_Graphs and Equilibrium Forces

Graphs
Topic Overview
•The motion of an object can be represented
by two types of graphs (x, v)
1) Displacement vs. Time graphs
X
(m)
A
B
Time (s)
•Tells you where the object is
•The slope (steepness) is the velocity
•In the graph above A is faster than B
Topic Overview
1) Types of Motion for x vs. t graphs
X
(m)
X
(m)
Time (s)
Not moving
because the
position does not
change
X
(m)
Time (s)
Constant velocity
because the
slope does not
change (linear)
Time (s)
Accelerating
because it is a
curve
Topic Overview
2) Velocity vs Time graphs
v
(m/s)
0
(s)
•Tells you how fast the object is moving
•Slope of the line = Acceleration
•Area under curve = Displacement
Topic Overview
2) Velocity vs. Time graphs
v
(m/s)
0
v
(m/s)
(s)
Constant speed
because the
value for velocity
does not change
0
v
(m/s)
(s)
Speeding up
because the value
of the velocity is
moving away from
zero
0
(s)
Slowing down
because the value
of the velocity is
moving toward
zero
Example Question-2
Example Question-2 Solution
Calculations with graphs!:
Example Question-1
Displacement: Difference
between y value
Average Speed: Slope between
2 time points
Instantaneous speed: Slope at
1 time point (TANGENT)
Example Question-1 Solution
Example Question-2
What is the
average
speed from
0-6 seconds?
Example Question-2 Solution
What is the
average speed
from
0-6 seconds?
Average is the slope
between 2 points
Slope = (4 – 0) = 0.66m/s
(6 – 0)
Example Question-3
What is the
displacement
from 1-4
seconds?
Example Question-3 Solution
Position
increased (+)
from 2m to
4m
Answer:
4 – 2 = 2m
Equilibrium Forces
Topic Overview
•A force is a push or a pull applied to an
object.
• A net Force (Fnet) is the sum of all the forces
on an object (direction determines + or -)
Fnet = 6N to the right
• Isaac Newton has laws that describe the
motion of object (I will go out of order….)
3rd Law: Equal and Opposite
▫ For every action, there is an equal and
opposite reaction.
▫ “Things push back”
1st Law: Law of inertia
▫ An object at rest will stay at rest unless acted
on by an outside force
▫ An object in motion will stay in motion
unless acted on by an outside force.
▫ Inertia: The amount of mass an object has
▫ More inertia = more mass = Harder to move
Topic Overview
•The first law is basically the law of
EQUILIBRIUM.
•When an object is in equilibrium, the net
force equals zero
•Equilibrium  Fnet = 0
Up = Down Forces
Left = Right Forces
• Objects in equilibrium can either be at
rest or be moving with constant velocity
Sample Problem
•What is the magnitude and direction of
the force that will establish equilibrium
on the block?