Force and Motion Flashcards
what does a straight line represent in a distance time graph
constant speed
what does a distance-time graph show
how the distance of an object changes over time
what does a flat, horizontal line mean in a d-t graph
stantionary
how to calculate speed in a d-t graph
gradient: rise/run
what does speed of an object mean
the distance it travels every second
average speed equation
distance moved/ time taken
accelration defenition
rate of change of velocity
acceleration equation
change in velocity/ time taken
object is slowing down
acceleration is negative
how to calculate acceleration on a v-t graph
gradient: rise/run
what does the area under a velocity time graph represent
displacement
how to calculate uniform acceleration
v^2=u^2 + 2as
how can forces affect bodies
change speed
change direction
change in shape
types of forces
gravitational
electrostatic
thurst
upthrust
air resistance
compression
tension
reaction force
gravitational
the force between 2 objects with mass
electrostatic
the force between 2 objects with charge
thrust
the force pushing on a vehicle
upthrust
the upward force on an object in fluid
eg. boat on river
air resistance
force of friction between objects falling through the air
compression
forces that squeeze an object
tension
forces that strech an onject
reaction force
the force between 2 objects in contact
scalar quantities
quantities with only a magnitude
vectors
both a magntitude and a direction
scalars
distance
speed
mass
energy
volume
density
temperature
power
vector
displacement
velocity
weight
force
acceleration
momentum
friction
the force which opposes the motion of an object
balanced forces
forces have combines in a way where they cancel each other out so there is no resultant force
unbalanced force
forces which do not cancel each other out so there is a resultant force on the object
force equation
F (N)= m (kg) x a (m/s^2)
weight
the force acting on an object due to gravitational attraction
weight equation
weight (N) = m(kg) x g (ms^-2)
mass
the amount of matter in an object
stopping distance
the total distance travelled during the time it takes for a car to stop response to some emergency
stopping distance equation
stopping distance= thinking distance + breaking distance
breaking distance
distance travelled under the braking force
thinking distance
distance travelled in the time it takes for the driver to react
factors which affect stopping distance
1) vehicle speed
2) vehicle mass
3) Road conditions
4) driver reaction time
what are the 2 forces an object experiences when it falls
weight
gravity
hookes law
the extension of an elastic object is directly proportional to the force applied, until the limit of proportionality
limit of proportionality
when more force is added, the object may extend but it wont return to its original shape when the force is removed
is hookes law linear or non linear
linear so it shows a straight line
elastic deformation
when the object returns to its original shape when the stretching force is removed
inelastic deformation
when the object remains stretched and does not return completely to its original shape even when the stretching force is removed.
momentum equation
p (kgm/s) = m x velocity (m/s)
does an object at rest have momentum
no
what does momentum depend on
direction of travel
the moment of an object changes if:
- change in acceleration
- change in direction
- its mass changes
conservation of momentum
in a closed system, the total momentum before an event is equal to the total momentum after the event
force equation 2
F= Change in P/ change in time
newtons third law
when 2 bodies interact, the forces they exert on each other are equal and opposit
how can the force of an impact in a vehicle collision be decreased
increasing the contact time
safety features in cars
crumple zones
seat belts
air bags
crash mats
thick and soft to offer shock absorption of the force which increases contact time
moment
the turning effect of a force about a pivot
moment eqaution
M (Nm) = F X d (m)
why is a door handle placed on the opposite side to the hinge
- creates a larger perpendicular distance
- which creates a larger moment to make it easier to open a door
principle of moments
if an object is balances, the total clockwise moment about a pivot is equal to the total anticlockwise moment about a pivot
Equation for conservation of moments
F2 x d2 = (F1X D1) + (F3 X d3)
a light beam is treated as if it has _________
no mass
centre of gravity
the point through which the weight of an object acts
- located at the point of symmetry
