Newton's Second Law Where every push turns into speed.

Feel the Push

Shopping cart being pushed

Everyday Force Example

Imagine pushing a loaded shopping cart.

The harder you push, the faster it moves; that push is a force.

Key Points:

  • Stronger push → bigger speed change
  • Heavier cart needs bigger push
  • Daily pushes help us feel force

Second Law: Words

Newton’s Second Law

Acceleration of an object is proportional to the net force applied and inversely proportional to its mass. More force → more acceleration; more mass → less acceleration for the same force.

The Famous Formula

\[F = m \times a\]

Newton squeezed the whole Second Law into this single line.

Variable Definitions

F Force (newton, N)
m Mass (kilogram, kg)
a Acceleration (m/s2)

Applications

Pushing a cart

More force makes the cart speed up faster.

Light vs heavy ball

With the same push, a lighter ball gains greater acceleration.

Force–Acceleration Graph

Force–Acceleration Graph

Graph for a 2 kg cart showing direct force–acceleration link.

Straight Line Shows Direct Proportionality

Consider a 2 kg cart pushed with varying forces.

On the Force (N) vs Acceleration (m/s²) graph, points lie on a straight line through the origin.

Key Points:

  • Line through origin ⇒ F ∝ a
  • Slope of line = mass = 2 kg
  • Each point follows \(F = m a\)

Check Point

Question

Formative assessment: A light toy car and a heavy grocery trolley receive the same push. Which one accelerates more?

1
Toy car
2
Grocery trolley
3
Both accelerate equally
4
Cannot say

Hint:

For a fixed force, acceleration is inversely proportional to mass: \(a = \frac{F}{m}\).

Key Takeaways

Force boosts speed

Greater force produces greater acceleration of the object.

Mass resists change

Heavier mass means smaller acceleration for the same force.

Rule in one line

Newton’s Second Law: \(F = m \times a\).

Quick recap

Force, mass and acceleration are linked; remember this whenever motion changes.