Key Concepts: Acceleration

What is Acceleration?

Acceleration is the rate of change of velocity with respect to time.

• a = Δv / Δt = (v_f − v_i) / t
• SI unit: m/s² (meters per second squared).
• Acceleration is a vector — it has magnitude and direction.

Key Ideas

• Positive acceleration: Velocity is increasing (speeding up in the positive direction, or slowing down in the negative direction).
• Negative acceleration: Velocity is decreasing in the positive direction (deceleration).
• An object can have zero velocity but nonzero acceleration (e.g., a ball at the top of its trajectory).
• Uniform acceleration: Acceleration is constant — produces a straight line on a v-t graph.

Graphical Interpretation

• On a velocity-time graph: acceleration = slope. Area under the curve = displacement.
• On a position-time graph: acceleration causes the curve to bend (parabola for constant acceleration).