SUVAT Equations

Overview

This lesson moves from graph language to equation language. SUVAT questions are usually won or lost before the calculation starts: identify the known quantities, choose a sign convention, and check that acceleration is constant.

What You Need to Know

• SUVAT equations apply to motion in a straight line with uniform acceleration.
• The key quantities are s, u, v, a, and t.
• You normally choose the equation that avoids the one quantity not mentioned in the question.
• Direction matters: quantities in the opposite direction to your positive choice must be negative.
• The equations can be linked back to velocity-time graphs and the definitions of velocity and acceleration.

How to Work Through It

1. List the SUVAT quantities and units before substituting numbers.
2. Decide which direction is positive and write down any negative quantities clearly.
3. Choose the equation that contains the known values and the target unknown.
4. Check whether the answer has a sensible sign, unit, and size.

Check Your Understanding

• What condition must be true before you use SUVAT?
• Which SUVAT quantity is missing from v^2 = u^2 + 2as?
• Why might displacement be negative even when the object is moving?
• How can a velocity-time graph help explain one of the SUVAT equations?

Common Mistakes

• Using SUVAT when acceleration is not constant.
• Mixing distance and displacement in the same calculation.
• Forgetting to make upward or backward quantities negative when needed.
• Rounding too early and losing accuracy in a multi-step question.

Next Steps

• Complete the SUVAT practice questions with full working, not just final answers.
• Keep your sign convention visible because it becomes essential in vertical motion.