A trolley moves along a track from P to Q. Its potential energy at Q is $50\,\text{kJ}$ lower than it is at P. At P, the trolley has kinetic energy of $5\,\text{kJ}$. As it travels from P to Q, it does $10\,\text{kJ}$ of work against friction. What is the kinetic energy of the trolley at Q?
- A$35\,\text{kJ}$
- B$45\,\text{kJ}$
- C$55\,\text{kJ}$
- D$65\,\text{kJ}$