Chapter 7 laws of motion and momentum Flashcards
(13 cards)
What is Newton’s First Law?
An object remains at rest or in uniform motion unless acted upon by a resultant force.
What is Newton’s Second Law?
The rate of change of momentum is proportional to the applied force: F = ma (for constant mass).
What is Newton’s Third Law?
For every action, there is an equal and opposite reaction.
What is momentum and its equation?
Momentum is the product of mass and velocity: p = mv.
What are the units of momentum?
Kilogram metre per second (kg·m/s).
What is the principle of conservation of momentum?
Total momentum of a closed system remains constant provided no external forces act.
What is impulse?
Change in momentum: Impulse = Force × time = Ft = Δp.
What are the units of impulse?
Newton seconds (N·s), which is equivalent to kg·m/s.
What is an elastic collision?
A collision where both momentum and kinetic energy are conserved.
What is an inelastic collision?
A collision where momentum is conserved but kinetic energy is not.
What happens to kinetic energy in an inelastic collision?
Some kinetic energy is converted into other forms like heat or sound.
How can you reduce the force in a collision?
Increase the time over which the force is applied (e.g., airbags, crumple zones).
Why are seatbelts and airbags effective?
They increase the time taken for momentum to change, reducing the force on passengers.
