1. The problem statement, all variables and given/known data A very short 100 kg acrobat steps off a 10 m high platform and starts falling. The acrobat falls 9 m, then encounters a 1 m long spring connected at one end to the ground below. (a) What’s the spring constant so the acrobat just touches the ground (that is, so the spring contracts 1 meter)? The spring-with-acrobat system rebounds and launches the acrobat back into the air. (b) How high off the ground does the acrobat go above the ground before falling back? 2. Relevant equations (1/2)k(x-x0)^2 mgΔh 3. The attempt at a solution To solve this, wouldn't one set the gravitational potential energy (mgh) to the spring potential energy (1/2kx^2) because the energy converts to one another, then solve for k? 1.96 * 10^4 N/m is the answer I got. For the second part of the problem, the acrobat will be the same exact height above the ground because the energy is conserved, right? Am I missing something in this problem? This was unexpectedly simple.