1. Motion Happy Teachers’ Day! From: II-Camia

2. Motion (pp. 126-128 Physics at Work 1) Motion is a change in the location of a body with respect to a reference point.

3. Speed is a scalar quantity which refers to how fast an object is moving. (distance over time) Velocity is a vector quantity. It is speed in a given direction or rate of change of displacement. * Scalar-has magnitude Vector-magnitude with direction Speed and Velocity

4. Average Speed The average speed is given by: The unit for speed is meters (meters) per second (m/s), kilometers per hour (kph), centimeters per second, and miles per hour (mph).

5. An MTR train takes 1267 seconds to travel a distance of 15.579 km from one end of the line to the other (first station to last station). This includes the stopover time of about 30 seconds at each station. What is the average speed of the train at kilometers per hour? Example (taken from book)

6. Given: distance=15.579 km ; time=1267 seconds Asked: speed of train in kilometers per second Equation: Solution: Because it is asking for kilometers per hour, we must first convert 1267 seconds. 1267 average speed=15.579km Solution 60x60 = 0.351944 hours 0.351944 hours = 44.3 kph

7. Acceleration Acceleration is the rate of change in velocity. If a driver steps on his accelerator, his car moves faster—it accelerates (positive acceleration). If he steps on his brake, his car slows down—it decelerates (negative acceleration or retardation). A change in velocity is given by the difference of the final velocity and the initial velocity. Thus, we have the equation: This is expressed in m/s s

8. Three Simple Equations of Motion Average speed Acceleration

9. Three Not-So-Simple Equations v=u+at v=final velocity u=initial velocity a=acceleration t=time taken

10. s=ut+1/2(at 2) s=displacement (distance from starting point) u=initial velocity t=time taken a=acceleration

11. V 2 -u 2 =2as v=final velocity u=initial velocity a=acceleration s=displacement

12. Example Eduardo is participating in a race, he stands on the starting line waiting for the race to commence. As soon as the signal to start was fired, he started running and finished the 45- kilometer racetrack in 20 minutes. Find 1.Distance 2.Time 3.Average velocity 4.Initial velocity 5.Final velocity 6.Change in velocity 7.Acceleration

13. Solution 1.Distance=45 km 2.Time=3 hours 3.Average velocity=9kph 4.Initial velocity=0kph 5.Final velocity=18kph 6.Change in velocity=18kph 7.Acceleration=6kph/h

14. Seatwork 1.Calculate the average speed of a.a TSK car running at 10 meters in 60 seconds b.a cat chasing a mouse 6 meters in 10 seconds c.sound traveling 6800 meters in 20 seconds d.a bullet moving 3000 meters in 3 seconds e.a jet aircraft traveling 36 kilometers in 1 minute 2.A body with an initial velocity of 8 m/s moves with a constant acceleration and travels 640 m in 40 seconds. Find its acceleration.

15. 3.A ball rolls down an inclined plane with a constant acceleration of 2.5 m/s 2 : a) how fast is the ball traveling after 3 seconds? b) how far has the ball traveled in those 3 seconds? c) how far has the ball traveled by the time its velocity is 15 m/s? 4.What velocity is attained by an object which is accelerated at 0.30 m/s 2 for a distance of 50. m with a starting velocity of 0.0 m/s? 5.A car starts from rest and accelerates uniformly to a velocity of 80 ft/s after traveling 250 ft. Find its acceleration.

16. For the following problems, please find a. distance b. time c. average velocity d. initial velocity e. final velocity f. change in velocity g. acceleration 6.If a calculator falls off the side of student desk and hits the floor 0.39 seconds later, how tall is the desk and how fast would the calculator be traveling when it hits the floor? (acceleration due to gravity is 9.8 m/s/s)

17. 8.What velocity would be attained by rolling ball which is accelerated at 0.30 m/s 2 over a distance of 50. m. The starting velocity was 0.50 m/s and the force that caused the acceleration was applied for 5.0 seconds. 9.You ride 300 miles to school but realized you forgot your Physics homework. You decide to go back to the house at a speed of 20mph, halfway there, someone brought it to you, so you rushed back to school at a speed of 30 mph. 10.An ice cream truck is moving along at 20 m/s (its initial velocity.) It then speeds up (accelerates) for 5 seconds at 8 m/s 2. What distance would the truck travel in this time interval?

18. Sources: www.sciencebyjones.com/PDF%20files/Physics%20 Information%202%20PDF.pdf Physics at Work 1