2. A spring has a natural length of 18 inches and a force of
20 lbs is required to stretch and hold the spring to a length of 24
inches. What is the work required to
stretch the spring from a length of 21 inches to a length of 26 inches? [Solution]
3. A cable that weighs kg/meter is lifting a load of 150 kg that is
initially at the bottom of a 50 meter shaft.
How much work is required to lift the load of the way up the shaft? [Solution]
4. A tank of water is 15 feet long and has
a cross section in the shape of an equilateral triangle with sides 2 feet long
(point of the triangle points directly down).
The tank is filled with water to a depth of 9 inches. Determine the amount of work needed to pump
all of the water to the top of the tank.
Assume that the density of water is 62 lb/ft3. [Solution]