M E N U
DIRECTIONS
1. USEFUL FORMULAS
2. THE CIRCLE (3 VARIATIONS)
• 3. THE SPHERE (2 VARIATIONS)
4. THE SQUARE (2 VARIATIONS)
5. THE CUBE (2 VARIATIONS)
6. THE RECTANGLE
7. THE AIRPLANE
8. THE SLIDING LADDER
9. MAKING SHADOWS
10. THE CONICAL TANK
11. THE CONICAL PILE
12. FLYING A KITE
13. REVOLVING SEARCHLIGHT
14. TRAVELING CARS (2 VARIATIONS)
15. MORE SHADOWS
16. THE BASEBALL FIELD
17. THE CYLINDRICAL TANK
18. EQUATION ONE (2 VARIATIONS)
19. EQUATION TWO (2 VARIATIONS)
20. EQUATION THREE (2 VARIATIONS)
21. EQUATION FOUR (2 VARIATIONS)
22. EQUATION FIVE (2 VARIATIONS)
23. EQUATION SIX (2 VARIATIONS)
24. EQUATION SEVEN
25. THE REVOLVING BEACON
26. THE ISOSCELES TROUGH
27. THE SPACE SHUTTLE
28. GONE FISHING
29. THE CLOCK
30. THE TRIANGLE #1
31. THE TRIANGLE #2
32. THE SNOWBALL
33. THE OTHER AIRPLANE
34. YET ANOTHER SHADOW
35. THE BASKETBALL SHADOW
36. MAKING COFFEE

EXPANDING SPHERE PROBLEM
VARIATION #2

The volume of a sphere is increasing at a rate of 720 ft3/sec. At the instant when the volume is 40.5 cubic feet, calculate the following:

(A) What is the length of the radius?


(B) At what rate is the radius changing?


(C) At what rate is the surface area changing?