Matter in Motion

1
Matter in Motion

• Chapter 1.1
• pp. 4-10

2
Motion

• How do we know something is moving?
• Is this guy in motion? How do you know?

3
Measuring Motion

• Must observe motion in relation to another object
• Reference Point an object that appears to stay
  in place in relation to an object being observed
  for motion
• (earth surface, tree, etc.)

4
Motion

• Motion object changing position over time when
  compared to a reference point
• Two elements position and time

5
Speed

• How do we know an objects speed?
• It depends on two factors
• distance and time
• Speed rate at which an object moves
• Ave speed total distance/total time

6
Speed on a graph
7
Velocity

• What if I said Johnny left CCMS and walked 1
  mile Can you know where he ended up? Why or
  why not?
• Velocity speed of an object in a particular
  direction
• Changes when SPEED or DIRECTION changes
• Sometimes can combine velocities

8
Combining Velocities

• If the train is moving forward at 70 mph and the
  guy throws the ball forward at 20 mph, how fast
  does the ball move according to the guy on the
  ground?
• 90 mph!

9
Combining Velocities

• If youre riding in a bus traveling east at 55
  mph, you and all other passengers are also
  traveling at a velocity of 55 mph east.
• But suppose you stand up and walk down the buss
  aisle at 2 mph west. Are you still moving at the
  same velocity as the bus?
• NO! And the resultant velocity is 53 mph east!

10
Combining Velocities

• When you combine two velocities that are in the
  same direction add them together to find
  resultant velocity!
• When you combine two velocities that in opposite
  directions subtract the smaller velocity to
  find the resultant velocity. This velocity will
  be in the direction of the larger velocity!

11
Acceleration

• Which is an example of acceleration?
• Sally slowed down to a stop at the end of her
  bike ride
• The light turned green so the car drove forward
• Sally was so excited to arrive in science class,
  she turned the corner into Mrs. Chamberlains
  room without changing her speed

12
Acceleration

• DOES NOT to speed up
• Acceleration the rate at which velocity changes
• In other wordschange of speed OR change of
  direction
• Acc (final velocity starting velocity)/time

13
Acceleration

• Positive acceleration speed increases
• Negative or deceleration speed decreases
• Change in direction change in acceleration