Kinematic Equations for Constant Acceleration
For constant acceleration: v = u + at, s = ut + at2/2, v2 = u2 + 2as.
What is Kinematic Equations for Constant Acceleration?
For constant acceleration: v = u + at, s = ut + at2/2, v2 = u2 + 2as.
Key formula / rule: Each equation drops exactly one of u, v, a, s, t.
Key points
- Derive the three equations of motion from the definition of constant acceleration.
- Select and apply the correct equation for a given data set.
- Analyse a reversing motion by splitting it into constant-sign intervals.
Common exam trap
Applying the equations across an interval where a changes, such as before and after braking.
Definitions
- Term
Kinematic Equations for Constant Acceleration
- Meaning
For constant acceleration: v = u + at, s = ut + at2/2, v2 = u2 + 2as.
- Term
Kinematic Equations for Constant Acceleration — explanation
- Meaning
The three equations are algebraic consequences of a constant slope in the v-t graph. Each omits one variable, so the choice of equation follows from which quantity is neither given nor asked. They are invalid the moment acceleration changes during the interval.
Learning objectives
Derive the three equations of motion from the definition of constant acceleration.
Select and apply the correct equation for a given data set.
Analyse a reversing motion by splitting it into constant-sign intervals.
Formulae
- Key point
Each equation drops exactly one of u, v, a, s, t.
- Key point
s here is displacement, not distance, so a reversing body needs interval splitting.
- Key point
Distance in the nth second: sn = u + a(2n-1)/2.
Prerequisites
PHY-U1-KIN-T1-S1-C3
Common mistakes
Applying the equations across an interval where a changes, such as before and after braking.
Using s as distance when the body reverses direction mid-interval.
Keywords
Kinematic
Equations
Constant
Acceleration
Practice preview
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