Motion and Forces Flashcards
what does it mean if the line is steep on a distance time graph
the greater the steepness the greater the speed of the object
examples of forces
weight
lift
electrostatic
tension
friction
thrust
magnestic
drag
contact
upthrust
what is a resultant force (and how do you calculate it)
if more than one force acts on an object you have to calculate the resultant force
(bigger force - smaller force = resultant force)
AND SAY THE DIRECTION
what happens if the resulant force is in the same direction as the object
the object will accelerate
what happens if the resultant force is in the opposite direction to the object
the object will decelerate
what happens if the resultant force is zero
the object will be stationary or moving at a contant speed
what is terminal velocity
The maximum speed of an object, reached when the forces moving the object are balanced by its frictional forces.
what is a scalar
a quantity that just has a size
what is a vector
a quantity which has size and direction
How can we tell Hooke’s law on a graph
on a force extension graph is the line is straight through 0 then the object is obeying the law
what does it mean if an object has elasticity
the object returns to its original shape after the force is removed
what are ways that force can affect the object that it is being applied on
change in shape
change in speed
change in direction
what is the equation between
stopping distance
breaking distance
thinking distance
of a car while it is stopping
stopping distance = thinking distance + breaking distance
what is the thinking distance
the distance the vehicle travels in the time it takes for th driver to apply the breaks after realising they need to stop
what are things that affect thinking distance
drugs, alcohol, distractions and tiredness
what is breaking distnace
the distance that an object travels from the time when the breaks are applied to the time when it comes to a complete stop
what factors affect breaking distance
speed of the vehicle, road conditions, weight of the vehicle, and slippery roads
what are safety features in roads
roundabouts
narrow lanes
speed bumps
traffic lights
stop signs
speed limits
what are safety features in cars
airbags
seatbelts
cruise control
headlights
breaklights
parking sound assists
what are many injuries in vehicle collisions and sporting injuries due to
the rapid acceleration of the body (they stop very quickly)
what can you do to the momentum to help improve the injury
by spreading the change in momentum over a longer time it recudes the force required to act which reduces the injury
explain how the seatbelt protects
it stretches so it increases the time to come to a stop
explain how a crumple zone protects
parts of the car are desgined to collapse so the car takes longer to stop moving
what is the conservation of momentum
total momentum before = total momentum after
what is a lever
an object rotating or trying to rotate
what is a pivot
the point around which the lever is rotating or trying to rotate
what is a moment
the turning effect of a force about a pivot
what is the principle of moments
clockwise moment = anticlockwise moment
what is the centre of gravity
the point in an object where all of the wright appears to act
how do you find the centre of gravity
if an object is placed such that it’s centre of gracity is on top of a pivot, the object will be balanced
why will the object be balanced when you find its centre of gravity
the perpendicular distance between theweight of the object and the pivot will be zero
what kind of quality is a force
vector
why do falling objects reach terminal velocity
the force of air resistance become large enough to blance the force of gravity
what is an investigation to investigate motion
a paper cone
a tennis ball
what is the aim to investigate motion
to investigate the motion of some every objects
what are the variables in investigating motion
independent - distance
dependent - time
control - use the same object for each measurement
what is the equipments needed to investigate motion
paper cone
stop clock
metre ruler
method for investigating motion
measure a high of 1.0m using the meter ruler
drop the object from this high (this will be the distance travelled)
use the stop clock to measure how long the object takes to travel the distance
record the distance and repeat steps for diferent hights
then calculate the speed
features of velocity time graphs
gradient = acceleration
flat sections means steady speed
the steeper the graph the greater the acceleration or deceleration
uphill means acceleration
downhill means deceleration
curve means changing acceleration
what does the area under a velocity time graph show
it is equal to the distance traveled in that time interval
how do you find acceleration on a V-T graph
vertical/horizontal
describe friction
if an object has no force accelerating it along then it will always slow down due to friction
this is because friction is a force that opposes motion
3 ways where friction happens
between solid surfaces
between solid surfaces sliding past each other
resistance or “drag” from fluids
what is static friction
when solid surfaces are gripping
what is sliding friction
sliding surfaces sliding past each other
can be reduced
what is resistance from fluid friction
e.g. Air resistance is a type of friction that slows the motion of an object moving through air
draw the forces acting on a moving car
what is gravity/weight
the force acting on an object due to gravity
what is electrostatic force
the force between 2 charged objects
what is thrust
Thrust is a force produced by an engine that speeds up the motion of an object
what is drag
Drag force is a type of frictional force that occurs when an object moves through a fluid
what is reaction force
the force that the object reacts back with
what is air resistance
Air resistance is a specific type of drag force and is therefore also a frictional force
Air resistance occurs when particles of air collide with an object moving through it and slows its motion
what is upthrust
When an object is fully or partially submerged in a fluid, the fluid exerts an upward-acting push force on the object
what is the investigation for hookes law with a spring
using a spring and masses
how to set up the investigation for hookes law with a spring
method for investigating hookes law with a spring
Align the marker to a value on the ruler with no mass added, and record this initial length of the spring / rubber band
Add the 100 g mass hanger onto the spring / rubber band
Record the mass (in kg) and position (in cm) from the ruler now that the spring / rubber band has extended
Add another 100 g to the mass hanger
Record the new mass and position from the ruler now that the spring / rubber band has extended further
Repeat this process until all masses have been added
Remove the masses and repeat the entire process again, until it has been carried out a total of three times, and an average length (for each mass attached) is calculated
what is elastic behavior
Elastic behaviour is the ability of a material to recover original shape after the force is removed.
what is newtons 1st law
balanced forces mean no change in velocity
what is newtons 2nd law
unbalanced forces
when a unbalanced force acts on an object it accelerates
what is newtons 3rd law
reaction forces
if an object exerts a force on another object there will be an equal and opposite force
when does an object reach terminal velocity
Eventually, the frictional force acting on the ball will become equal to the weight of the ball.
what does hookes law look like when the force is great enough
what is resistance measured in
ohms
