p2 Flashcards
(58 cards)
how do you calculate weight
mass times gravitational field strength
W=mg
how do you calculate work done
force*distance
how do you calculate kinetic energy
KE= 1/2 mv^2
how do you calculate elastic potential energy
E=1/2 ke^2
k is the spring constant obviously
e is extenstion
what factors affect stopping distance
speed
reaction time
braking force
what is newton’s FIRST law
an object remains at rest or moves at a constant velocity unless acted upon by a resultant force
what is newtons SECOND la
force=mass*acceleration
what is newton’s THIRd law
for every action there is an equal and opposite action
how do you calculate speed
speed= distance/time
how do you calculate acceleration
change in velocity/time
REMEMBER THIS: how to interpret distance time and velocity time graphs
in distance time graphs: slope/gradient is speed
area under curve isn’t anything lol
but in velocity time graphs: slope is acceleration
area under curve represents distance
how do you measure distance in different situations
measure distances:
use ruler for small distances
use tape measure or trundle wheel for longer distances
in car or speed experiments, use a measuring wheel or GPS for accurate tracking
how can you measure distance and time to calculate speed using graphs
on a distance time graph gradient is speed
speed=d/t
difference between scalar and vector quantities
scalars have magnitude only (size)
distance, speed, time,mass
vectors have magnitude and direction:
displacement,velocity,force,acceleration
how do distance and velocity time graphs show changes in motion
DISTANCE TIME
straight line= constant speed
curved line= acceleration/deceleration
steeper slope= faster speed
VELOCITY TIME
straight horizontal line= constant velocity
sloped line= constant acceleration
steeper slope= faster acceleration
line sloping down=deceleration
what does the area under a velocity time graphs represent
distance travelled
for uniform motion= distance= velocity*time
for non uniform motion= area of shapes under line
add together to find total distance
how do you calculate average speed for non uniform motion
average speed= total distance/ total time
what formulas can you use for motion, including with constant acceleration
uniform motion
speed=distance/time
uniform acceleration; (constant)
v=u+at
v^2=u^2+2as
s= displacement
how do you measure time in different situations
stopwatch - reaction based
timer/data loggers- digital device that automatically records time more accurately
light gates-electric sensors used for school experiments;
— setup where a beam of light is sent betwen 2 points
— when something passes through the gate, it breaks the beam, timer stops
— no human reaction error
examples of how objects interact
exert forces on each other:
gravitational: earth pulls object down
electrostatic- two charged balloons repel or attract
magnetic- magnets attraction or repel each other
contact-pushing or friction between surfaces
how do interactions between 2 objects produce forces
according to newtons 3rd law
when two objects interact, they exert equal and opposite forces on each other
interaction pairs- forces are always:
equal in size
opposite in direction
acting on different objects
how do we show forces using vectors and diagrams
forces are vectors, they have both magnitude and direction
arrows to represent
length of arrow= how big the force is
direction- which way force acts
gravity=arrow pointing down
normal contact force= arrow pointing up from a surface
friction- arrow pointing opposite to motion
what are free body diagrams
simple diagrams showing:
all the forces acting on a simple object
no other objects drawn- just arrows + labels
