Math Calculus question

Question

A chain lying on the ground is 10 ft long and weighs 110 lbs. How much work is required to raise one end of the chain to a height of 7ft?

Answer 1

Work = Force x Distance

Units of work are Joules, Force in Newtons and Distance in Meters

You've only lifted 7 feet of the 10 foot chain, the other 3 feet remain on the ground. 7/10 of 110 lbs = 77 lbs. But you didn't move all of the 7 feet of chain up 7 feet. Divide by 2, on average you moved it up 3 1/2 feet. Convert to Newtons, also convert 7 feet to meters and multiply to get work in joules

there's a trig function in the standard work formula, but if you moved it straight up, it drops out.