Post on 02-Jan-2016
transcript
Laws of Motion
Mr. Dunnum
Physical Science
Key terms
MotionSpeedAverage SpeedInstantaneous SpeedVelocityAcceleration
What is motion?
Motion is when an object of any sort is changing positions
Fast moving airplane Swirling of the wind Trickle of water
Distance and Displacement
• Displacement includes the distance between the starting and ending points and the direction in which you travel.
This figure shows the difference between distance and displacement
What is speed?
Speed is the distance traveled divided by the time taken to travel the distance
Olympics runners run the 100m in 10s, which equals 10m/s or meters per second
Video
Practice problem
Calculate the speed of a swimmer who swims 100 m in 56s
What you know: Distance: 100m Time: 56sEquation: Speed= distance/timePlug it in: Speed= (100)/(56)Answer: Speed=1.8m/s
Problem
A runner completed a race of 400 m in 43.9s. In a 100m race he finishes in 10.4s. Which race was his speed faster.
100=9.6 m/s
Average Speed
Average speed is found by dividing the total distance traveled by the time taken
Intermediate sprinterNever runs the race at the same speed
the entire time so you will have to get an average speed.
A trip to Atlanta
Instantaneous Speed
When an object is in motion it changes speeds many different times
The speed of an object at one instant of time is instantaneous speed
For example a car accelerating 0-60 in 5 secs
Velocity/Acceleration
Velocity
The velocity of an object is the speed of the object and direction of its motion
Car traveling n 60mph then turns west and continues at 60mph. Does the velocity change?
Acceleration Means simply a change
in velocity Acceleration is more
than speeding up Acceleration is not how
much velocity changes but how fast.
Video
Examples of acceleration/velocity
Examples of acceleration Examples of velocity
A plane taking off Increase in speed
A car stopping at a stop sign Decrease in speed
Jogging a winding trail Change in direction
Driving around a corner “
Standing on the Earth’s equator “
Rocket launching “
Examples of acceleration/velocity
Examples of acceleration Examples of velocity
A plane taking off Increase in speed
A car stopping at a stop sign Decrease in speed
Jogging a winding trail Change in direction
Driving around a corner “
Standing on the Earth’s equator “
Rocket launching “
Calculating acceleration
Acceleration= final velocity- starting velocity time it takes to change velocity
A plane passes over point A with a velocity of 8000m/s north. 40 sec. later it passes over Point B at a velocity of 10,000 m/s north. What is the acceleration from A to B.
50m/s/sNegative acceleration is also called decceleration