**A horizontal spring with spring constant 210 N/m is compressed by 10 cm and then used to launch a 250 g box across the floor. The coefficient of kinetic friction between the box and the floor is 0.23. What is the box’s launch speed?**

**Answer:**

**A horizontal spring with spring constant 210 N/m is compressed by 10 cm and then used to launch a 250 g box across the floor. The coefficient of kinetic friction between the box and the floor is 0.23. What is the box’s launch speed?**

**Answer:**