The diagram represents the energy transfers when a compressed spring launches a trolley. The spring's elastic store decreases by 5.0 J. The trolley starts from rest.
elastic store→Xkinetic store of trolley \text{elastic store}\xrightarrow{X}\text{kinetic store of trolley} elastic storeXkinetic store of trolley elastic store→0.8 Jthermal stores \text{elastic store}\xrightarrow{0.8\ \mathrm{J}}\text{thermal stores} elastic store0.8 Jthermal storesThe trolley has mass 0.30 kg. Which is its speed just after launch, to two significant figures?
3.7 m/s3.7\ \mathrm{m/s}3.7 m/s
5.3 m/s5.3\ \mathrm{m/s}5.3 m/s
5.8 m/s5.8\ \mathrm{m/s}5.8 m/s
28 m/s28\ \mathrm{m/s}28 m/s