Motion- Chapter 1 pp
Speed- a measure of how fast something is moving. Equation- Speed = distance time You have to MEMORIZE this one!
Units for speed- mi/h (mph) km/h or m/s ( / is read per and means divided by) Use this to remember the equation!
1.) What is the speed of a car that has gone 200 km in 4 hrs.?
200km = 50 km/hr 4 hr Answer-
Velocity- describes the speed and direction of something You can change velocity without changing speed if you turn a corner. If you travel at 10mph on Lombard street your speed stays the same. 2.) Does velocity change? Answer: Yes, several times
Velocity vector- a pictorial representation of velocity An arrow that shows the direction of travel Length of the arrow shows the speed of object
Vectors can also represent other quantities like force Shows the direction of the force. Length of the arrow = magnitude of the force
Adding vectors Vectors that add together – Component Vectors (arrows A & B) The sum of component vectors is called a resultant ( arrow C) You cannot add velocity vectors with force vectors or acceleration vectors A C B A B Add vectors by lining them up “tip to tail” End up with a parallelogram
Acceleration- the rate of change in velocity Acceleration = change of velocity time interval
Units for Acceleration- km/hr 2 Reads kilometers per hour per hour Each hour the speed changes so many kilometers per hour m/s 2 Reads meters per second per second Each second the speed changes so many meters per second km/h/sReads kilometers per hour per second Each second the speed changes so many kilometers per hour
3.) A car can go from 0 km/h to 90 km/h in 10 s. What is its acceleration?
90 km/h – 0 km/h = 9 km/h/s 10 s These units are the hardest to understand! 4.) What do these units mean? Answer- This answer means that each second the car is speeding up 9 km/h
Free Fall (Vertical Velocity)- an object falling free of all restraints v = gt –v- velocity –g- acceleration of gravity »9.8 m/s 2 on earth »during each second of fall the object gains 9.8 m/s in velocity –t- time
Calculating Vertical Distance- Freely falling objects only Equation- d = ½ gt 2 –d = distance traveled »Units- meters –g = acceleration due to gravity »Units- m/s 2 –t = time of fall »Units- seconds
5.) A person jumps off a cliff and has been falling for 1.3 sec., how far did they fall?
Answer: d = ½ gt 2 d = ½ x (9.8) x (1.3) 2 d = 4.9 x 1.69 d = 8.28 meters 6.) Why are the units meters? The units on 9.8 are m/s 2.
Done!!