-- Lance Armstrong decides to go for a bike ride. He starts at a speed of 10 m/s, but then decides to go downhill. Downhill he speeds up at a constant rate. His overall descent is 150m and takes him 10s. ------- How fast is he going at the end? 15m/s
150/10=15 ------- By what amount did his velocity increase every second? .5m/s he sped up 5m/s in 10s, thats half a meter per second.
-- You hike 2/3 up a mountain at a speed of 3mi/hr and run the final third at 6mi/hr. Average speed?
You first divided the hike into thirds
You hike 1/3 at 3 mph, you hike 1/3 at 3 mph, you hike 1/3 at 5 mph.
3+3+6=12
12/3=4
This is simply knowing what to divided
-- a horse moves away from its trainer in a straight line, 116m away in 14s. It turns and gallops halfway back in 4.8s. Calculate average speed, and average velocity, away is positive.
116/2=58
116+58=174
first average speed is 8.29(rounded)
second average speed is 12.08(rounded)
You once again divide into three parts, 1/3 at 8.29, 1/3 at 8.29, 1/3 at 12.08
2(8.29)+12.08=28.66
28.66/3=9.55(rounded)
9.55s to run 58m
6.07 m/s
I think I may be wrong, I rounded a lot.
Some more complex things: -- A falling stone takes .28s to travel past a window 2.2 m tall. From what height above the top of the window did it fall?