Transcript Matter&Motion

Matter & Motion
Isaac Newton
1643 – 1727
Newton, age 46
Newton, age 82
Motion – Terms & Definitions
• Speed = rate of change of position
e.g., miles/hour, meters/second
• Velocity = speed in a specific direction
e.g., 20 meters/sec, north
20 kilometers/sec, up
• Acceleration = rate of change of velocity
* requires change in speed and/or direction

Auto goes from 0 to 90 mph
in 7 sec: accelerated motion
Auto rounds curve at constant
40 mph: accelerated motion
Catch a baseball – ball stops:
accelerated motion
Laws of Motion
1. In the absence of a net force, an object moves
with constant velocity.
* Force = “push or pull”
Laws of Motion
1. In the absence of a net force, an objects tend to
maintain constant velocity.
2.
force
accelerati on 
mass
F

a  
m

3. For every action force, there exists an equal and
opposite reaction force:
action = reaction
Falling through
the
atmosphere . . .
Net force is combination of
air resistance and gravity.
air resistance
gravity
If gravity exceeds air resistance,
then person accelerates.
Catching a ball . . . again:
FH  Force on hand due to ball
FB  Force on ball due to hand
FH = FB
FH
FB
Rocket Propulsion . . .
Rocket pushes on exhaust;
exhaust pushes on rocket.
Forces are equal!
Yeah!