# How much work does it take to raise a 31 kg  weight 52 m ?

I got $15 , 797.6 J \approx 15.8 k J$
You do work against gravity so you need to put in at least the same force as $m g$ (the weight) to go for a displacement of $h = 52 m$;
$W = m g h = 31 \cdot 9.8 \cdot 52 = 15 , 797.6 J \approx 15.8 k J$