So, to calculate the acceleration of an object, you divide the change in its velocity, by the time taken for that change. In physics, change is always calculated as the final value minus the initial value. So, if Jerry is going at $$10 \, \mathrm{m/s}$$ and his velocity becomes $$30 \, \mathrm{m/s}$$, the change in velocity is $$20 \, \mathrm{m/s}$$.
We saw that Jerry's velocity changed from $$2.5 \, \mathrm{m/s}$$ at $$2 \, \mathrm{s}$$ to $$5 \, \mathrm{m/s}$$ at $$4 \, \mathrm{s}$$. What is his acceleration in $$\mathrm{m/s^2}$$?
• $$\frac{2.5 - 5}{2}$$
• $$\frac{5 - 2.5}{2}$$
• $$\frac{2.5 + 5}{2}$$
• $$\frac{2.5 + 5}{2 + 4}$$