Transcript Chap-8-Accel-Momentum.

Constant speed
A Data Table
constant velocity
Time
0 sec
Position
1 meter
Velocity
= dist/time & direction
1 sec
2 meters
1 m/s to right
2 sec
3 meters
1 m/s to right
3 sec
4 meters
1 m/s to right
Position-Time Graphs
Distance (ft) Vs. Time (sec.)
200
Distance in Feet
160
120
80
40
0
1
2
3
4
5
6
7
Time in Seconds
8
Describes the Rate of Change in
Position of an Object Over Time
9
Position-Time Graph
160
Distance in Feet
The
constant
slope
indicates
that the
speed of the
object
remains
constant
Distance (ft) Vs. Time (sec.)
200
120
80
40
0
1
2
3
4
5
6
7
Time in Seconds
8
9
The Slope of this Line Remains
Constant Throughout the Graph
Position-Time Graph
Distance (ft) Vs. Time (sec.)
200
160
Distance in Feet
The Speed of
This Object
Changes
Over Time
The Object is
Accelerating
C
120
80
B
40
0
1
2
A
3
4
5
6
7
8
9
Time in Seconds
Speed @A = 5 ft/sec
Speed @B = 24 ft/sec
Speed @C = 50 ft/sec
Slope  Velocity
Changes in Velocity
10 m/s,
downward
25 m/s,
downward
Velocity changes
in both these cases.
25 meters per second,
45 degrees upward
25 meters per second,
45 degrees downward
Interpret The Graph Below:
Balanced vs Unbalanced forces
Momentum
*Depends on what two things?
a. Mass
b. Velocity
P = mv
Units – kg. m/s, direction

1. Two hockey players, big Joe and little Tim
collide head on and get tangled while going
for the puck. 65 kg Tim was travelling at 9.5
m/s while 105 kg Joe was moving at 5.2 m/s.
Who will go in which direction, and what is
their momentum before the collision?
Interpret The Graph
Below:
Interpret The Graph
Below:
Interpret The Graph
Below:
Acceleration

a=
v/t
a=acceleration,v=velocity
=change, t=time

*Change in velocity divided by the time
interval in which the changed occurred

Units - m/s2, direction
A missile was released from an airplane at
the velocity of 78 km/hr south and ended
up traveling at a velocity of 104 km/hr
south. It took the missile 1 hour to reach
the target. Find the missile’s acceleration.
1.What do they want to know?
2. Which formula do I use.
3. Plug in the numbers.


A dog runs with an initial speed of 1.5 m/s
on a waxed floor. It slides to a stop with
an acceleration of -.35 m/s2 . How long
does it take for the dog to stop?
A football player likes to practice knocking
the other players of their feet. He has a
mass of 624.8 kg and created a
momentum of 3124 kg. mph as he flatten
a teammate. What was his velocity when
he hit his teammate?
1.What do they want to know?
2. Which formula do I use.
3. Plug in the numbers.


YouTube - smart car crash
Force
 Cause
of acceleration, or change
in an object’s velocity
F
= ma, units – N, newtons
1 newton = .225 lb
Net force
Combination of all of the forces
acting on an object
Gravity & Friction
Gravity
 Attraction of two particles of matter due to
their mass
 Mass & Distance effects it
 9.8 m/s2

Friction
 Force between two objects in contact that
opposes the motion of either object

Explain what is happening
Weight

Elevator
Is your weight the same on earth as it is
on the moon?
 Is your mass the same on earth as it is
on the moon?


Mr. Dovzak