I need a little help on this one: One end of a massless spring is welded to a flat surface, the other points upward. A mass of 1.0kg is gently set down on top of the spring until the spring is compressed by 17cm to a new equilibrium position. What is the spring constant? I know that you can find the spring constant by using F=-kx but I don't know how to find it without knowing the force. If anyone could help me I would greatly appreciate it. Thankyou!!