This document contains physics problems and questions about concepts such as acceleration, speed, velocity, free fall, and reaction time. It provides example problems and calculations related to these topics, asking the reader to determine values like acceleration from given speeds and time intervals, instantaneous and average speeds, and distances fallen over time when objects are dropped. The document also lists homework problems for students to complete that involve applying concepts like calculating average speed from distance and time, instantaneous speed at a given time, and personal reaction time from a vertical jump.

1. Physics L4 www.slideshare.net/DMS_physics

2. Key Terms acceleration average speed elapsed time free fall instantaneous speed rate relative scalar speed vector velocity

3. Class Review Problems P.25 / 12 P.26 / 18, 21, 28, 30 P.27 / 52 P.26 / 32

4. p.25 / 12 What is the acceleration of a car that travels in a straight line that increases its speed from zero to 100 km/h in 10s ?

5. p.26 / 18 Toss a ball upwards. What is the change in speed each second on the way up ? on the way down ?

6. p. 26 / 21 How far will a freely falling object have fallen from a position of rest when its instantaneous speed is 10 m/s ?

7. p.26 / 26 Calculate the average speed of a cheetah that runs 140 m in 5 s.

8. p.26 / 28 Calculate the acceleration of a car that can go from rest to 100km/h in 10s.

9. p.26 / 30 Calculate the speed of a skateboarder who accelerates from rest for 3s down a ramp at an acceleration of 5m/s 2 .

10. Reaction Time (p.27/52) Calculate the reaction time of a person by dropping a ruler and letting the other person catch it. Measure the distance dropped in this time What is the reaction time?

11. p.26 / 32 An object is dropped from rest and falls freely. After 6s, calculate its: instantaneous speed average speed distance fallen

12. Homework Assignment P.26 / 27, 29, 33, 53

13. Homework Assignment P.26 / 27 A) calculate the average speed of Charlie, who runs to the store 4km away in 30 min. B) calculate the distance that Charlie runs if he maintains this average speed for 1h.

14. Homework Assignment P.26 / 29 Calculate the instantaneous speed at the 10s mark for a car that accelerates at 2m/s 2 from a position of rest.

15. Homework Assignment P.26 / 33 Calculate the instantaneous speed and distance for an object that that falls freely from rest for 8 seconds.

16. Homework Assignment P.26 / 53 Calculate your personal “hang time”, the time your feet are off the ground during a vertical jump.

17. Homework Assignment P.26 / 27, 29, 33, 53 (for problem texts see previous slides)

18. End L4 www.slideshare.net/DMS_physics