Answer:
7200 N/m
Step-by-step explanation:
Metric unit conversion
100g = 0.1 kg
5 cm = 0.05 m
50 cm = 0.5 m
As the block is released from the spring and travelling to height h = 1.5m off the ground, the elastics energy is converted to work of friction force and the potential energy at 1.5 m off the ground
The work by friction force is the product of the force F = 15N itself and the distance s = 0.5 m

Let g = 10 m/s2. The change in potential energy can be calculated as the following:

Therefore, as elastic energy is converted to potential energy and work of friction:


