A trolley moves up a slope with an initial speed of 6.0 m/s. At the highest point it is momentarily at rest. During the ascent, 13\displaystyle \frac{1}{3}31 of its initial kinetic energy is transferred to thermal stores. Use g=10 N/kgg=10\ \mathrm{N/kg}g=10 N/kg. What vertical height does the trolley gain?
1.2 m1.2\ \mathrm{m}1.2 m
0.6 m0.6\ \mathrm{m}0.6 m
1.8 m1.8\ \mathrm{m}1.8 m
2.4 m2.4\ \mathrm{m}2.4 m