What is accuracy?
How close the measurement is to the accepted value
The degree to which you measure
The skill of the experimenter
The level of uncertainty
The smallest scale increment on a measuring device is the...
Precision
Accuracy
Reliablity
Uncertainty
What does the level of uncertainty depend on?
Number of repeats
All experiments are uncertain
Which of these are systematic errors?
experimental set up
Human error
faulty equipment
inconsistent parallax error
reaction time
Zero errors on meters
Which of the following does not apply to random errors?
They reduce the accuracy
The reduce the precision
They can never be fully eliminated
Systematic errors can be totally eliminated
When adding or subtracting measured quantities, how do we find the uncertainty?
Add the absolute uncertainty of each
Add the percentage uncertainty of each
Multiply the percentage uncertainties together
Use the biggest absolute uncertainty
When multiplying or dividing quantities, how do we find the uncertainty?
Add the percentage uncertainty
Multiply the percentage uncertainties
Add the absolute uncertainties
Double the uncertainty
What is a scalar quantity?
A quantity with magnitude only
A quantity with magnitude and direction
Which of these are scalar quantities?
Distance
Speed
Velocity
Current
Acceleration
Mass
Density
How do you combine scalar quantities?
Add them
Multiply them
Resolve them
Momentum is a vector
Force is a scalar
How do you combine parallel vectors?
Add/subtract them
Multiply/divide them
Make them into a triangle and use pythagoras
How do you combine vectors that are at random angles relative to each other?
Add their magnitude and their angles
Use the parallelogram rule
Upthrust is...
The force on an object due to the difference in pressure when immersed in a fluid.
The contact force of water
The opposite of gravity
Weight is...
The force on an object due to gravity
Gravity
The mass of an object
What is the pulling force exerted by a string, chain, cable or similar object?
Tension
Normal reaction force
Weight
Upthrust
What is friction
A force resisting the parallel movement of two surfaces in contact
A force that slows down objects
A force which prevents objects from sliding
Which of these are fundamental forces?
Strong Nuclear
Weak Nuclear
Gravitational
Electromagnetic
In which direction does weight act?
Vertically downwards
Perpendicularly downwards to the object
Parallel to the surface
In which direction does the normal reaction force act?
Vertically upwards
Perpendicular to the surface producing it
Perpendicular to the object
Parallel to the object
If an object is in equilibrium it is static
What does equilibrium mean?
There are no forces acting on a body
There is no resultant force
A body is completely still
A body is balanced
What is a moment?
The turning effect of a single force
force x distance
force x perpendicular distance
weight x distance
force/distance
A pair of forces that are equal and opposite
The forces on an object
What is the principle of moments?
The sum of the clockwise moments of an object = the sum of the anticlockwise moments of an object
If an object is in equilibrium: the sum of clockwise moments = the sum of anticlockwise moments
The sum of anticlockwise moments on an object can never fully equal the sum of clockwise moments on an object
A couple of forces is two forces that are equal and opposite and acting in the same line
What is torque?
The moment of a couple
Fd
Fd/2
The resultant of two perpendicular forces
The distance of forces from the pivot
What is pressure measured in?
Nm^-2
Nm^2
N/m
Pa
Pressure = perpendicular force/area
Pressure = density x height x gravity
