A trolley moving right has mass 500 g. A force of 1.8 N pulls it right and a force of 0.3 N opposes its motion. What is its acceleration?
0.0030 m s−20.0030\ \mathrm{m\,s^{-2}}0.0030 ms−2 rightwards
3.6 m s−23.6\ \mathrm{m\,s^{-2}}3.6 ms−2 rightwards
4.2 m s−24.2\ \mathrm{m\,s^{-2}}4.2 ms−2 rightwards
3.0 m s−23.0\ \mathrm{m\,s^{-2}}3.0 ms−2 rightwards