The amount a string stretches varies linearly with the mass applied to the spring, as can be seen in the video. in the video, with no additional mass, the hanger was 30.6 cm off the ground. with 150 grams of additional mass, the hanger was 16.2 cm off the ground. a wooden block stretched the spring so the hanger was 24.9 cm off the ground. determine the mass of the wooden block, to at least 1 decimal place.