CPM Homework Help : PC Problem 10-73

Go back to problem 10-63 and compute the average speed of the Ice mobile over each of the following time intervals. Be sure you pay attention to the direction the car is traveling. You will need your graph.

Hint:

average speed = total distance / total time

$0$ to $30$ seconds

$60$ to $70$ seconds

$80$ to $100$ seconds

Step 1:

When $t = 0$ , the Icemobile is at $\left(600, 1250\right)$ .
When $t = 30$ , the Icemobile is at $\left(600, 900\right)$ .

Find the total distance, or distance between the two points, and the total time.

Step 2:

total distance = $\sqrt{\left(600 − 600\right)^2 + \left(900 − 1250\right)^2 }= 350$ ft

Step 3:

total time $= 30 − 0 = 30$ seconds

Answer:

average speed $= 350/30$ feet per second

Now try parts (b) and (c).

Answers:

b: $20$ ft/sec
c: $17.68$ ft/sec