3.5 Newton’s Laws of Motion and Momentum Flashcards
What is Newton’s first law
An object will remain at rest or continue to travel with constant velocity unless acted on by a resultant force
What is Newton’s second law
The net force acting on an object is directly proportional to the rate of change of momentum, and acts in the same directions
What are the equations associated with newtons second law
Force (N) = change in momentum (kgms-1) / time (s)
F = Δp / t = (mv - mu) / t
Force (N) = mass (kg) x acceleration (ms-2)
F = ma
What is Newton’s third law
When two object interaction they exert equal and opposite forces on each other
These are always forces of the same type and magnitude but they act on different objects and in opposite directions
What is linear momentum and state its units
The product of an objects mass and velocity
Kilogram metres per second (kgms-1)
What is the equation for linear momentum
Momentum (kgms-1) = mass (kg) x velocity (ms -1)
p = mv
What is an impulse
The measure of change in momentum
The product of the force and time for which it acts
What is the equation for an impulse
Impulse (Ns) = force (N) x change in time (s)
Δp = FΔt
What is represented by the area under a force-time graph
The impulse
What happens in an elastic collision
Particles collide and move away from each other
Momentum is conserved
Kinetic energy is conserved
What happens in an inelastic collision
Particles collide and move away together
Momentum is conserved
Some kinetic energy is transferred to other forms (sound/heat)
Total energy is the same
What types of collisions are ‘sticky’
Elastic
Inelastic
What happens in an explosive collision
Particles initially at rest and then fly apart
Momentum is conserved as x and y direction both resolve to 0N
