题目

A man, whose ability to walk was threatened after a car accident in his teens, completed a 200-mile cycle across Baffin Island in the Arctic. It took him eight days to complete the  36  . This man was Ben Rockett, aged 26 and from Taunton, England.     He battled  37   temperatures of minus 27℃ and winds up to 100 knots to raise more than $1,000 for the charity Action for Children. Ben had to cycle in  38   conditions, but was helped with a(n)  39   designed bike. He spent months 40   for the challenge with David Hempleman-Adams, who was the first person to reach the 17．如图所示，带电量为q的正电荷在匀强电场中由A运动到B，若AB距离为L，L沿电场线方向的投影距离为d，电场强度大小为E，则：（1）电场力做功与电势能变化有何关系？电势能与电势有何关系？电势差与电势有何关系？（2）你能根据（1）推导出电势差与电场强度的关系吗？