Science Physics Flashcards
distance
- scalar quantity
- length of space covered between 2 points during an objects motion
displacement
- vector quantity
- objects overall change in position
- always measured from the 0 point in metres
speed
- scalar quantity
- how fast an object is moving
- rate which an object covers distance
velocity
- vector quantity
- rate at which an object changes its position
- does not tell anything about what happens to it between starting point and ending point
- if velocity changes, motion is accelerating.
acceleration
- vector quantity
- rate at which an object changes it velocity
- object is accelerating if the velocity is changing
- require an outside force such as gravity
- object with negative acceleration could be speeding up and object with positive acceleration could be slowing down
scalars
quantity described by a magnitude only
vectors
quantity described by both magnitude and direction
newton’s first law
- velocity of an object will remain constant unless acted upon by a net unbalanced force
example: ball will continue rolling but friction makes it slow down and eventually stop
newton’s second law
- net external force acting on a body is directly proportional to and in the same direction as the acceleration of the body
- force = mass x acceleration
example: skydiver jumps from a plane and accelerated until reaching highest velocity point but acceleration is 0. air resistance is equal to downward force of skydiver.
newton’s third law
- for every action, there is an opposite and equal reaction
example: presses on wall and wall pushes back for there is an equal and opposite force
inertia
- represented by newton’s first law
- object tends to stay at rest or continue motion unless acted by a force
- greater the mass, greater the inertia (harder to stop)
physics
- precisely define the most fundamental measurable quantities in the universe
- find relationships between fundamental measured quanities
instantaneous speed
-speed of an object at a particular moment in time
magnitudes of the instantaneous speed and velocity are always identical
instantaneous velocity
-velocity of an object at a particular moment in time
smaller displacement/ shorter time interval
position vs. time graphs
- horizontal line = no motion
- slope = velocity in x direction
- vertical axis = position of object
- slop represents velocity of the object
x2 - x1
———- = slope/velocity
t2 - t1
- if velocity/slope is constant, the acceleration is 0
velocity vs. time graphs
- vertical axis = velocity of object
- slope represents acceleration of the object
v2 - v2
———- = slope/acceleration
t2 - t1
- area = displacement
- area under graph represents displacement of the object
acceleration vs. time graphs
- vertical axis = acceleration of object
- slope represents quantity called ‘jerk’, rate of change of the acceleration
a2 - a1
———– = slope/ rate of change of acceleration
t2 - t1
- area under graph represents change in velocity
area = change in velocity
4V = v - u
if acceleration is high
velocity is changing rapidly
if acceleration is 0
velocity is exactly constant
ticker timer
- machine that makes a series of dots on paper as it moves through the machine
- each length of tape (6 dots) represents 0.1s
d (length of tape)
V= —————————
t (0.1s) - measures speed and/or acceleration
calculate resultant force
add forces acting on an object together (30N + 25N = 55N)
acceleration by newton’s equation
a = force/mass
momentum
- quantity of motion of a moving body.
momentum (p) = mass x velocity
weight
- force of gravity on an objects mass
weight (w) = mass x gravitational acceleration (g)
gravity
- point at which whole weight of object appears to act
- sometimes referred to as the center of mass
m1-m2
F= G ———–
(v)^2
gravity on earth = 9.8m/s^2 (x weight of object = Newton weight)
mass
the ‘stuff’ or matter made up of in an object
newton’s law of gravity
- between 2 objects there is a force of attraction
- greater masses, stronger gravitational force
- distance between masses increases, gravitational force decreases
stopping distance of a car - speed at which a car stops is dependent on
- reaction/thinking time
- reaction/thinking distance
- braking distance
reaction/ thinking time
time it takes for information to pass from eyes to brain and leg to push the brake
reaction/ thinking distance
distance the car travels in the reaction time
braking distance
distance car travels between when brakes are applied and when the car stops. dependent on:
- condition of brakes
- condition of tires
- weather conditions
- road conditions
total braking distance is measured in
- thinking distance
- braking distance
- total braking distance
thinking distance
how FAR the car travels whilst the driver reacts
braking distance
DISTANCE TRAVELED after driver puts foot on brake
total braking distance
SUM of braking and thinking distance
