GenPhysics1: Forces - Collision

Q: What is force?

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

Q: 1 Newton is equal to?

A: 1 N = 1 kg·m/s²

Q: Tool used to measure force?

A: Spring balance.

Q: What is a contact force?

A: Force that requires direct physical touch between objects.

Q: Examples of contact forces?

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

Q: What is a non-contact force?

A: Acts at a distance, without touching.

Q: Examples of non-contact forces?

A: Gravitational, magnetic, electric.

Energy

Q: What is energy?

A: The ability to do work.

Q: Formula for Kinetic Energy (KE)?

A: KE = ½ mv²

Q: Formula for Gravitational Potential Energy (GPE)?

A: PE = mgh

Q: Formula for Mechanical Energy (ME)?

A: ME = KE + PE

Q: Law of Conservation of Energy?

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

Momentum

Q: What is momentum?

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

Q: Units of momentum?

A: kg·m/s

Q: Impulse formula?

A: Impulse = Force × Time = Change in momentum.

Q: Why do airbags and parachutes reduce injury?

A: They increase collision time, reducing impact force.

Q: Law of Conservation of Momentum?

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

Collisions & Explosions

Q: What is a collision?

A: Short interaction between objects that transfers KE and momentum.

Q: What is an explosion?

A: Opposite of collision—objects move apart after intense interaction.

Q: Elastic collision definition?

A: Momentum and KE are conserved. Objects bounce off.

Q: Perfectly elastic collision?

A: No KE lost, objects bounce with no speed loss.

Q: Inelastic collision definition?

A: Momentum conserved, KE lost.

Q: Perfectly inelastic collision?

A: Objects stick together after collision; KE loss is maximum.

Q: Formula for final velocity in inelastic collision?

A: vf = (mA vA + mB vB) ÷ (mA + mB)