Motion — practice question

An object’s velocity changes from $30\,\text{m s}^{-1}$ to $50\,\text{m s}^{-1}$ over $5.0\,\text{s}$. What is the object’s average acceleration?

• A$0.10\,\text{m s}^{-2}$
• B$0.25\,\text{m s}^{-2}$
• C$4.0\,\text{m s}^{-2}$
• D$10\,\text{m s}^{-2}$