Retrieval Questions Flashcards
When is a measurement valid
When it measures what it is supposed to be measuring
When is a result accurate
When it is close to the true value
What are precise results
When repeat measurements are consistent with each other
What is repeatability
How precise repeated measurements are when they are taken by the same person using the same equipment under the same conditions
What is reproducibility
How precise repeated measurements are when they are taken by different people using different equipment
What is the uncertainty of a measurement
The interval within which the true value is expected to lie
Define measurement error
The difference between a measured value and the true value
What type of error is caused by results varying around the true value in an unpredictable way
Random error
What is a systematic error?
a consistent difference between the measured values and true values
What does zero error mean?
a measuring instrument gives a false reading when the true value should be zero
Which variable is changed or selected by the investigator?
independent variable
What is a dependent variable
A variable that is measured every time the independent variable is changed
Define a fair test
a test in which only the independent variable is allowed to affect the
dependent variable
What are control variables?
variables that should be kept constant to avoid them affecting the dependent variable
What is a physical quantity?
a property of an object or of a phenomenon that can be measured
What are the S.l. units of mass, length, and time?
kilogram (kg), metre (m), second (s)
What base quantities do the S.l. units A. K, and mol represent?
current, temperature, amount of substance
List the prefixes, their symbols and their multiplication factors from pico to tera (in order of increasing magnitude)
Write it out
What is a scalar quantity?
a quantity that has magnitude (size) but no direction
What is a vector quantity?
a quantity that has magnitude (size) and direction
What are the equations to resolve a force, F, into two perpendicular components, Fx and Fy?
Fx =Fcos0
Fy = F sin0
What is the difference between distance and displacement?
distance is a scalar quantity
displacement is a vector quantity
What does the Greek capital letter 🔺 (delta) mean?
Change in
What is the equation for average speed in algebraic form?
V =🔺x /🔺t ( change in x over change in t)
What is instantaneous speed?
the speed of an object over a very short period of time
How can you calculate acceleration from a velocity-time graph?
acceleration is the gradient
displacement is the area under the graph
Write the equation for acceleration in algebraic form.
a = 🔺v/🔺t
What do the letters suvat stand for in the equations
of motion?
s = displacement
u = initial velocity
v = final velocity
a = acceleration
t=time taken
Write the four suvat equations.
s = ut + 1/2at^2
s = 1/2(u+v)t
v = u+at
v^2 = u^2 +2as
Define stopping distance
the total distance travelled from when the driver first sees a reason to
stop, to when the vehicle stops
Define thinking distance
the distance travelled between the moment when you first see a reason to stop to the moment when you use the brake
Define braking distance
the distance travelled from the time the brake is applied until the vehicle
stops
What does free fall mean?
when an object is accelerating under gravity with no other force acting on it
