8.1MechanicsStretch

Vectors in Kinematics

Motion in two dimensions is described with vectors. Position, velocity and acceleration become vector quantities, and the constant-acceleration (suvat) equations work in vector form.

24 min Video by Zeeshan Zamurred Further Kinematics

Edexcel A Level Maths: 8.1 Vectors in Kinematics (Part 1)Watch the full walkthrough before the notes below.

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What you'll be able to do

Use position, velocity and acceleration vectors
Apply suvat in vector form
Find displacement and velocity at a time
Work with i, j components

Vector suvat

For constant acceleration, the suvat equations hold as vectors. For example $v = u + a t$ and $s = u t + \frac{1}{2} a t^{2}$ , each applied component by component.

v = u + a t, s = u t + \frac{1}{2} a t^{2}

suvat in vector form.

v = (3 i + j) + 2 (i - 2 j)

= 5 i - 3 j

Answer

5 i - 3 j

Tip — Apply each suvat equation separately to the i and j components.

Formula recap

v = u + a t

Velocity.

s = u t + \frac{1}{2} a t^{2}

Displacement.

Common mistakes to avoid

Adding the magnitudes of vectors directly.

Work component by component.

Forgetting suvat only applies for constant acceleration.

Use calculus methods when acceleration varies.

Key takeaways

Position, velocity, acceleration are vectors.
suvat holds in vector form for constant acceleration.
Work component by component (i and j).

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