1. Speed, Distance, Time Calculations

2. The aim of this lesson is to be able to use the correct formulas to calculate speed, distance or time

3. 15 mins = 0•25 hour 30 mins = 0•5 hour 45 mins = 0•75 hour
Reminder: How to change minutes into a decimal
15 mins = 0•25 hour
So: 3 hours 15 mins = 3•25 hours
30 mins = 0•5 hour
So: 7 hours 30 mins = 7•5 hours
45 mins = 0•75 hour
So: 2 hours 45 mins = 2•75 hours

4. The 3 formulas for Speed, Time & Distance:
Speed x
Time
Solving for Speed
Solving for Time
Solving for Distance D S T
Remember them from
this triangle:

5. A windsurfer travelled 28 km in 1 hour 45 mins.
Calculate his speed.

6. Answer: His speed was 16 km / hour
A windsurfer travelled 28 km in 1 hour 45 mins.
Calculate his speed.
Distance
Time D S T
Speed = 28
1•75 =
1 hour 45 mins
= 16 km/h
Answer: His speed was 16 km / hour

7. A salesman travelled at an average speed of 50 km/h for 2 hours 30 mins. How far did he travel?

8. Answer: He travelled 125 km
A salesman travelled at an average speed of 50 km/h for 2 hours 30 mins. How far did he travel? D S T
Distance =
Speed x Time
= 50 x 2•5
2 hour 30 mins
= 125 km
Answer: He travelled 125 km

9. A train travelled 555 miles at an average speed of 60 mph
A train travelled 555 miles at an average speed of 60 mph. How long did the journey take?

10. Answer: It took 9 hours 15 minutes
A train travelled 555 miles at an average speed of 60 mph. How long did the journey take? D S T
Distance
Speed
Time =
555 60 =
= 9•25 hours
= 9 hours 15 mins
Answer: It took 9 hours 15 minutes

11. Speed Formula # 2
a = v 2 – v1 t
Acceleration = (speed 2 – speed 1) ÷ time

12. Example:
Q: What is the rate of acceleration for a car that accelerates from 0 m/sec to 30 m/sec in 10 seconds?
a = v 2 – v1 t

13. Solution:
a = ( 30 – 0) = 3m/s 2 10

14. Try speed formula # 2
A roller coaster’s velocity at the top of a hill is 10m/s. Two seconds later it reaches the top of the next hill with a velocity of 26 meters/second. What is the acceleration of the coaster?

15. Solution:
a = a=8 m/s 2 2

16. FLASH BACK NOV. 12 What does the prefix “kilo” stand for?
a.) b.) c.) 1,000
Calculate the distance traveled by a mountain goat traveling 10 mph over 3 ½ hours.
a.) .35 miles b.) 35 miles c.) 350 miles
3. Calculate the time it took for a bull frog to cross the pond that is 500 meters wide if he is traveling at a speed of 10 meters per second.
a.) 50 seconds b.) 5 seconds c.) 500 seconds

17. Analysis & Conclusion
What combinations of height and marble size caused the greatest acceleration of the marble? What caused the least acceleration of the marble? *Acceleration is any change in speed or direction; that means that when the marble slows down or turns it is accelerating.

18. Complete the section review questions on: #1 -3, p.9 #1 – 3, p.13
Read Ch. 1 in Text Book
Complete the section review questions on: #1 -3, p.9 #1 – 3, p.13

19. Physics Test 1
Add your multiple choice, scantron score (total of 24 pts. Possible) + Your Extended Response score 4 pts possible

20. Flash Back Nov. 14
Determine the DISTANCE traveled by a herd of horses galloping at a speed of 40 mph over 5 hours.
a.) 200 miles b.) 220 m c.) 240 m
2. What does velocity have that speed does not?
a.) acceleration b.) direction c.) speed
3.What type of wave moves in the traditional up & down fashion?
a.) transverse b.) longitudinal c.) electromagnetic