Energy Conservation with Conservative Forces: a Spring-Loaded Dart Gun Is

Energy conservation with conservative forces: A spring-loaded dart gun is used to shoot a dart straight up into the air, and the dart reaches a maximum height of 24 meters above its point of release. The same dart is shot up a second time from the same gun, but this time the spring is compressed only half as far (compared to the first shot) . How far up does the dart go this time? (Neglect friction and assume the spring is ideal and massless.)

A) 6.0 m
B) 12 m
C) 3.0 m
D) 48 m