A powered cart moves along a level track. The table shows the constant driving force and distance travelled during each stage. The driving force acts in the direction of motion, and resistive forces oppose the motion.
| Stage | Driving force in N | Distance in m |
|---|---|---|
| 1 | 150 | 8.0 |
| 2 | 200 | 5.0 |
The cart's kinetic energy store increases by 1.4 kJ. Assume all the energy transferred that does not increase the cart's kinetic energy store increases thermal stores.
Calculate the increase in thermal stores.