EOY Flashcards
Elastic deformation
When an object returns to its original shape when the stretching force is removed
equation with force, spring constant and extension
f = ke
equation for elastic potential energy
EPE = 1/2ke^2
Inelastic deformation
when an object does not return to its original shape when the stretching force is removed. Therefore, it is left permanently stretched
What is Hooke’s Law?
The extension of a spring is directly proportional to the force applied to it, as long as its limit of proportionality is not exceeded.
Limit of proportionality
The limit of proportionality is where if more force is added, the object will not return to its original shape when the force is removed
How to tell if object contains elastic potential energy?
it will return to its original shape
Explain why adjusting the ruler was important
to reduce error in measuring the extension of the spring
the ruler at an angle will make the measurements shorter
how to know if something is directly proportional
straight line
that passes through the origin
Technique to improve measuring extension
attach a pointer to the bottom of the spring
so it goes across the ruler scale
The stiffer the spring
the greater the spring constant, therefore more force is required per metre of extension
spring constant on a force-extension graph
is the gradient
steep straight line on force-extension graph =
small spring constant
work done is
the transfer of energy
Elastic potential energy
The energy stored in an elastic object when work is done on the object
types of errors
systematic error (zero error) random error
Newton’s Second Law of Motion?
When a resultant force acts on an object, it produces an acceleration (or deceleration)
What is Newton’s First Law of Motion?
If no resultant force acts, an object will remain stationary or move at a constant speed in the same direction
What is Newton’s Third Law of Motion?
When two objects interact with each other, they exert equal and opposite forces on each other
effects on stretched coil
the length of the coil has increased
length of the loops has stretched
spring has stretched
why are mean values given to 2 dp if results are 3 dp?
stopwatch reacts to 0.01 s
reaction time is less precise than a stopwatch
acceleration
the rate of change of velocity
change in velocity / time taken
velocity
the rate of change of displacement
accelerate
changed velocity
speed of sound
330 m/s
human walking speed
1.5 m/s
human running speed
3 m/s
human cycling speed
6 m/s
distance in a velocity-time graph
area under the graph
How to calculate reaction time
measure the distance the ruler falls before being stopped - the greater this distance the greater the reaction time
repeat measurements and calculate mean
why were anomalous result during reaction time
the student was distracted
stopwatch started before the computer test was started
How would you increase speed of a car
make it more streamlined
reduce the weight
increase power of engine
contact forces
forces that act between objects that are physically touching e.g. tension friction air resistance reaction force
resultant force
a single force that has the same effect as all the forces combined operating on an object
why does acceleration decrease even though the force remains constant
as speed increases air resistance increases
reduces the resultant force
why might an object continue at the move at a constant speed in the same direction
the resultant force is equal to 0
so the object will move at the same speed in the same direction
if an object is more streamlined
the air resistance is smaller
so the object can reach a higher speed
distance in a velocity-time graph
1/2 x base x height
Explain how the wheel can move at a steady speed and the capsules accelerate at the same time.
acceleration occurs when the direction of each capsule changes
acceleration is the rate of change of velocity
scalar quantities
have size (magnitude) but no specific direction e.g. speed, direction, mass, temperature & time
vector quantities
have both magnitude and direction
e.g. force, acceleration, displacement, velocity & weight
What are waves
are repeated vibrations that transfer energy from one place to another