GenPhysics1: Forces - Collision

What is force?

A push or pull acting on an object due to interaction. SI unit: Newton (N).

1 Newton is equal to?

1 N = 1 kg·m/s²

Tool used to measure force?

Spring balance.

What is a contact force?

Force that requires direct physical touch between objects.

Examples of contact forces?

Normal, friction, tension, air resistance, applied, spring.

What is a non-contact force?

Acts at a distance, without touching.

Examples of non-contact forces?

Gravitational, magnetic, electric.

What is energy?

The ability to do work.

Formula for Kinetic Energy (KE)?

KE = ½ mv².

Formula for Gravitational Potential Energy (GPE)?

PE = mgh.

Formula for Mechanical Energy (ME)?

ME = KE + PE.

Law of Conservation of Energy?

Energy cannot be created or destroyed, only transformed. Total ME is constant.

What is momentum?

The product of an object’s mass and velocity (p = mv).

Units of momentum?

kg·m/s.

Impulse formula?

Impulse = Force × Time = Change in momentum.

Why do airbags and parachutes reduce injury?

They increase collision time, reducing impact force.

Law of Conservation of Momentum?

In an isolated system, total momentum before = total momentum after.

What is a collision?

Short interaction between objects that transfers KE and momentum.

What is an explosion?

Opposite of collision—objects move apart after intense interaction.

Elastic collision definition?

Momentum and KE are conserved. Objects bounce off.

What is a perfectly elastic collision?

No KE lost, objects bounce with no speed loss.

Inelastic collision definition?

Momentum conserved, KE lost.

What is a perfectly inelastic collision?

Objects stick together after collision; KE loss is maximum.

Formula for final velocity in inelastic collision?

vf = (mA vA + mB vB) ÷ (mA + mB).