Aheavy rope, 50 ft long, weighs 0.5 lb/ft and hangs over the edge of a building 120 ft high. how much work is done (in ft-lb) in pulling half the rope to the top of the building?

The formula used in calculating for values of work is given as:

W = F d

However on the above formula, the force is constant but i this case, it is changing. Therefore we make use of the general form with the integral notation: 
W = ∫F(x) dx

with limits of x from 0 to 25 since only half of the rope is be pulled

The equation for F (x) is equal to the product of mass density and length x:
F(x) = 0.5x 
Substituting this into the integral work equation:
W = 0.5∫x dx

W = 0.5(0.5) [x2^2 – x1^2]                  ---> x from 0 to 25

W = 0.25 [25^2 -0]

nah.   i'm just sleepy.

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.