GCSE Science Velocity and Distance-Time Graphs

Velocity and Distance-Time Graphs

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acceleration is how quickly the velocity is changing
change in velocity can be change in speed or change in direction or both
acceleration = change in velocity/time taken
Gradient=Acceleration
Flat represents steady speed
Steeper the graph the greater the acceleration and deceleration
Atrea under any section of graph is equal to the distance travelled in that time
Curve means changing acceleration

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resultant force is the overall force on a point or object
there are at least two forces acting upon an object
to work out the resultant force, you add or subtract the forces
if there is a resultant force then the object will change velocity, change its position

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if the resultant force on an object is zero, the object will remain stationary
if there is no resultant force on a moving object, it will remain at the same velocity
a resultant force means acceleration
if there is a non-zero resultant force, then the object will accelerate in the direction of the force
any resultant force will produce acceleration, the formula is F=ma or a =F/m
m: mass in kilograms (kg)
a: acceleration in metres per second squared
F: is the resultant force in Newtons (N)
reaction forces are equal and opposite ( two forces are acting on different objects)

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friction slows things down
if an object has no force it will slow down and stop because of friction
friction acts in the oppoiste dtrection to movement
to travel at steady speed, driving force needs to balance frictional forces
you get friction between two surfaces in contact, or when an object passes through fluid (drag)
most resistive forces are caused by air resitance or drag
most important factor to reduce drag in fluids is keeping object streamlined
drag increases as speed increases
objects falling through liquids reach a terminal velocity

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when falling objects set off, gravity much more than frictional force slowing down, so accelerate
as speed increases the friction builds up
this reduces the acceleration until frictional force is equal to the acceleration force, then it wont accelerate anymore
it will have reached its terminal velocity and will fall at a steady speed

if there was no air resistance, all objects would fall at the same speed as gravity acts upon all objects
on earth, air resistance causes things to fall at different speeds and terminal velocity is determined by drag in comparison to weight
frictional force depends on shape and area

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when force moves object through a distance energy is transferred
Work done = Force * Distance
gravitational potential energy is due to height
Gravitational Potential Energy = mass * g * height
this is measured in joules
this is the energy that an object has by virtue of vertical position and gravitational field, when an object is raised vertically, work is down against the force of gravity and object gains gravitational potential energy.

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kinetic energy is of movement
anything that is moving has kinetic energy
Kinetic Energy = 1/2 * mass * speed squared
kinetic energy depends on mass and speed
the more it weighs and the faster its going, the bigger the kinetic energy will be
to slow something down, the kinetic energy needs to be converted into other types of energy
conservation of energy states that energy can never be destroyed or created only converted into different forms
1/2mv(squared) = F * d
m: mass of car
v: speed
F: maximum force
d: breaking distance
when something falls its potential energy is converted into kinetic energy
so the further it falls, the faster it goes

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