Constant acceleration equations
Objective. Select and apply SUVAT equations with sign conventions.
- 1. Learn
- 2. Worked example
- 3. Practice
- 4. Feedback
- 5. Continue
Learn: the key idea
The constant acceleration equations, often called SUVAT equations, link displacement s, initial velocity u, final velocity v, acceleration a and time t when acceleration is constant: v=u+at, s=ut+½at², v²=u²+2as, and s=½(u+v)t. You select the equation containing the three known quantities and the one unknown you need. For example, if u=0, a=2, t=5, you can find v using v=u+at=0+2(5)=10. Always define a consistent positive direction before substituting signed values into these equations.
Worked example
A car accelerates from rest at 3m/s² for 4 seconds. Use the constant acceleration equations to find its final velocity.
- 1Use v=u+at since u, a and t are known
- 2Here u=0, a=3, t=4
- 3v=0+3×4
- 4v=12m/s
Answer: 12m/s
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Practice
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Start practisingCommon mistake. Students mix sign conventions, treating deceleration as positive acceleration without adjusting other signed quantities. Always fix one positive direction first and apply it consistently across u, v, a and s.
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