5. Newton's Laws of Motion + Momentum

What is Newton’s first law?

An object will remain at a constant velocity unless a resultant force acts on it

What is Newton’s second law + equation?

• Newton’s second law - the resultant force on an object is proportional to the rate of change of momentum of the object

• F = Δp / Δt (force = change in momentum / change in time)

What is the special equation for Newton’s second law?

F = ma (force = mass x acceleration) for when mass is constant

What is Newton’s third law?

If object A exerts a force on object B then object B exerts an equal + opposite force on object A

What is the equation for momentum?

p = mv (momentum = mass x velocity)

What is a property of momentum + equation?

• Property - momentum is always conserved (e.g before + after collisions)

• m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

What do elastic + inelastic collisions mean?

• Elastic - KE conserved

• Inelastic - KE not conserved (e.g lost to surroundings through heat)