The right half will be a new bar magnet of 2cm with north pole on the right side and south pole on teh left.
Change in speed = (acceleration) x (time)
4 minutes = 240 seconds
Change in speed = (40 m/s²) x (240 seconds)
Change in speed = <em>9,600 m/s</em>
What you're actually describing here is a car pulling 4 G's for 4 minutes, and ending up going 21,475 miles per hour.
The driver would definitely NOT get a speeding ticket, because nobody could catch him.
Also, his car would heat up and shoot flames from atmospheric friction.
(He could avoid this with some fancy steering, leave the atmosphere, and end up in low-Earth-orbit.)
Actually, I hope there's nobody in the car. His experience wouldn't be pretty.
The work that you do on the lever will be the same as the work done by the lever on the rock. This aligns with the Law of the Conservation of Energy which states that energy can not be created nor destroyed. Since work can be calculated as force applied over a distance, you will apply a smaller force but your distance will be longer. The lever will apply a greater force over a shorter distance in proportion to yours. Therefore, the same amount of work is done on both sides of the lever.