A trolley of mass 2.0 kg moves at 3.0 m/s. What is its kinetic energy?
3.0 J3.0\ \mathrm{J}3.0 J
6.0 J6.0\ \mathrm{J}6.0 J
18 J18\ \mathrm{J}18 J
9.0 J9.0\ \mathrm{J}9.0 J