A pinball machine launches an 84 g ball with a spring-driven plunger. The game board is inclined at 12 degrees above the horizontal. Assume: The plunger’s mass and frictional effects are negligible. The acceleration of gravity is 9.8 m/s 2. Find the force constant k of the spring that will give the ball a speed of 108 cm/s when the plunger is released from rest with the spring compressed 4 cm from its relaxed position.

Answer in units of N/m.