2. MOTION MECHANICS Change in PositionReference Point Distance Time

3. Scalar Vector DistanceDisplacement SpeedVelocity Acceleration

6.  It is a scalar quantity which refers to how fast an object is moving.  Speed can be thought of as the rate at which an object covers distance.

7.  A fast-moving object has a high speed and covers a relatively large amount of distance in a given amount of time.

8.  A slow-moving object has a low speed and covers a relatively small amount of distance in a given amount of time.

9. Speed = Distance Time

10.  It is a vector quantity which refers to the rate at which an object changes its position.  Velocity is a vector quantity. As such, velocity is direction-aware. When evaluating the velocity of an object, one must keep track of direction.

11. Velocity= Distance Time + Direction

12. 1. Ave watches a thunderstorm from his window. He sees the flash of lightning and begins counting the seconds until he hears the clap of thunder 5.0 seconds later. Assume that the speed of sound in air is 340.0 m/s. How far away was the lightning bolt?

13.  In last week's Homecoming victory, Al Konfurance, the star halfback of South's football team, broke a tackle at the line of scrimmage and darted upfield untouched. He averaged 9.8 m/s for an 80-yard (73 m) score. Determine the time for Al to run from the line of scrimmage to the end zone.

14. 2. A car starts from rest and attains a speed of 50 m/s in 15 seconds. How far has the car travelled in 15 seconds? 3. If it takes you 45 seconds to run 340 meters, what is your average speed? 4. How long does it take a skier to travel 650 meters, going 18.5 m/s?

15.  Acceleration is a vector quantity which is defined as the rate at which an object changes its velocity.  An object is accelerating if it is changing its velocity.

16. Acceleration = Force Mass Acceleration = Final velocity – Initial velocity Time

17.  Since acceleration is a vector quantity, it has a direction associated with it.  The direction of the acceleration vector depends on two things: 1. whether the object is speeding up or slowing down 2. whether the object is moving in the + or - direction

19.  Suzie Lavtaski has reached the end of the ski slope and abruptly decelerates from 29.0 m/s to 1.8 m/s in 1.45 seconds. Determine Suzie' acceleration.  The Lamborghini Murcielago can accelerate from 0 to 27.8 m/s (100 km/hr or 62.2 mi/hr) in a time of 3.40 seconds. Determine the acceleration of this car.

20.  A Formula One car is a single-seat racing car with an open cockpit and substantial wings located in the front and rear. At high speeds, the aerodynamics of the car help to create a strong downward force which allows the car to brake from 27.8 m/s (100 km/hr or 62.2 mi/hr) to 0 in as small of a distance as 17 meters. Determine the deceleration rate (i.e., acceleration) achieved by such a car.

21.  A skater moving at 5 m/s begins to decelerate at a rate of 1 m/s 2. How fast will the skater be moving after 4 s?  An object starting from rest attain a 34 m/s velocity after 300 s. Determine the object’s acceleration.

22.  Suzie Lavtaski has reached the end of the ski slope and abruptly decelerates from 29.0 m/s to 1.8 m/s in 1.45 seconds. Determine Suzie' acceleration rate and the distance she moved during this braking period.

23.  A bus traveling at a speed of 50 m/s is increasing its speed at the rate of 4 m/s 2. Find the distance covered in 6s.

24. 1. What velocity is obtained by an object which is accelerated by 0.3 m/s² for a distance of 50 meters if the initial velocity is 0.5 m/s? Given : a = 0.3 m/s 2 d = 50 m V 0 = 0.5 m/s Unknown : V or V f Solution : V 2 = V o 2 + 2ad

25.  A Cessna 150 airplane has a takeoff speed of 28 m/s (63 mi/hr). Determine the minimum length of the runway which would be required for the plane to take off if it averages an acceleration of 1.9 m/s/s.

26.  A car has uniformly accelerated motion and starting from rest, has a velocity of 24.4 m/s after traveling 76m. Find its acceleration.

27. 4. A ball with initial velocity of 10 m/s rolls down an inclined plane with uniformly accelerated motion. If its acceleration is 20 m/s², find: a. Its velocity at the end of 10 sec, b. The distance it travelled in 10 sec, and c. Its distance after 8 sec.

28. 1. An ice cream truck is moving along at 20 m/s as its initial velocity. It then speeds up (accelerates) for 5 seconds at 8 m/s². What distance would the truck travel in this time interval?

29. 2. What velocity would be attained by a rolling ball which is accelerated at 0.30 m/s²? The starting velocity was 0.50 m/s and the force that caused the acceleration was applied for 5 seconds.

30. 4. An oceanic depth-sounding vessel surveys the ocean bottom with ultrasonic waves that travel 1530 m/s in seawater. How deep is the water directly below the vessel if the time delay of the echo to the ocean floor and back is 6 s?

31. Uniformly Accelerated Motion Free-falling Body With Initial Velocity Initial Velocity = 0 With Initial Velocity Initial Velocity = 0 Vf = Vi + atVf = atVf = Vi + gtVf = gt d = Vi t + ½ at²d = ½ at²d = Vi t + ½ gt²d = ½ gt² Vf = √Vi² + 2adVf = √2adVf = √Vi² + 2gdVf = √2gd d = Vi + a (2t – 1 sec) 2 t = √2d g

32. 1. If Marie decides to walk across town to a store that is 95 kilometers away and she has only 25 minutes to get there, what speed does she need to maintain to arrive on time? 2. A car accelerates at a rate of 0.6 m/s 2. It took this car 2 seconds to increase its velocity of 55 m/s to its final velocity. What is the car’s V f ?