Answer:
8.2 *10^5 ft lb
Step-by-step explanation:
Wcoal = 800*500 = 400000 = 4*10^5 ft lb
Using a right Riemann sum
The width of the entire region to be estimated = 400 - 0 = 400
Considering 8 equal subdivisions, then the width of each rectangular division is 400/8 = 50
F(x) = 6(400-y)
Wrope = 50(2100) + 50(1800) + 50(1500) + 50(1200) + 50(900) + 50(600)
+ 50(300) + 50(0) = 420000 = 4.2 * 10^5 ft lb
Note: Riemann sum is an approximation, so may not give a accurate value
work done = Wcoal + Wrope= 4*10^5+ 4.2 * 10^5 = 8.2 *10^5 ft lb