P10 - Force and Motion Flashcards
describe:
how terminal velocity is reaced for a parachutist
- accelerate because the force of weight downwards > force of drag upwards, Newton’s second law
- reaches terminal velocity when weight = drag, Newton’s first law
- opens parachute, more particles hit the parachute which increases drag upwards
- he deaccelerates because weight < drag, Newton’s second law
- reaces 2nd terminal velocity when weight = drag again, Newton’s first law
define:
Newton’s First law of motion
a body will continue to do what it is doing unless a resultant force is exerted on it
define:
Newton’s Second law of motion
if the forces on a body are unbalanced, the body will accelerate
accelerate - change in direction or velocity
define:
Newton’s Third law of motion
every action has an equal and opposite reaction
define:
resultant force
the sum of all forces on a body
define:
inertia
the tendency of an object to continue in its state of rest or of uniform motion
equation:
Newtons Second law of motion
F = ma
define:
inertial mass
a measure of how difficult it is to change the velocity of an object
define:
mass
a measure of quantity of matter
define:
weight
force acting on a mass due to gravity
what two factors determine stopping distance
of a car
- Thinking distance
- Breaking distance
list:
what affects thinking distance
of a car, 5 examples
- speed
- tiredness
- alcohol
- drugs
- distractions (phone)
also anything that increases reaction time
list:
what affects breaking distance
of a car, 3 examples
- speed
- road conditions (icy / wet)
- worn brakes
formula:
momentum
p = mv
define:
conservation of momentum
the total momentum before an event is equal to the total momentum after an event
formula:
conservation of momentum
pA + pB = 0
pA = -pB
remember the negative
formula:
force
using time
F = (m Δv) / t
explain:
crumple zones
they increase impact time
therefore rate of change of momentum decreases
therefore impact force decreases
formula:
Hooke’s law
F = ke
k = spring constant, e = extension
define:
elasticity
the ability of an object to return to its original shape after being stretched or compressed
define:
Hooke’s law
the force applied to a spring is directionally proportional to the extension of it, as long as its limit of proportionality is not exceeded
F = ke
