Mass And Weight Flashcards
what does the gradient of a distance-time graph represent
the speed of an object
what is velocity
its speed in a particular direction
what does the slope on a distance time graph represent?
the acceleration of an object
how to find acceleration on the graph
velocity / time in s
what does the gradient of a velocity-time graph represent?
the acceleration
what does the area under a velocity time graph represent
the distance covered
what is mass
how much stuff there is in a object
what is weight
how much including gravity the mass weighs.
how is weight calculated
mass x gravitational field strength
how is ‘work done’ calculated
force x distance
what is density
mass per unit volume
how to calculate density
mass / volume
how can you measure density of an irregular shape
water displacement using an eureka can. the volume of the object is equal to the volume of the water that is forced through the spout
what is newtons first law of motion
objects with greater mass will resist change in motion more that objects with less mass.
how do you calculate resultant forces
mass x acceleration
what is hooke’s law?
when an elastic object such as a spring it stretched, the increased length is called it’s extension. the extension of an elastic object is directly proportional to the force applied to it.
how to measure force
constant x extension
why would the equation not work
when the limit of proportionality is exceeded.
what is the extension
the new length minus the unloaded length
what is the gradient of the line called
the spring constant, k
what does the greater the value of k mean
the stiffer the spring
what is newtons second law of motion
the relationship between force mass and acceleration
what happens if the mass is the same
more force causes more acceleration
less force causes less acceleration
what happens if the force is the same
more mass causes less acceleration
less mass causes more acceleration
what happens if the acceleration is the same
more mass needs more force
less mass needs less force
how can force be calculated
mass x acceleration
what is pressure
pressure is the force per unit area
how to calculate pressure
force / area
how to increase pressure
increase the force or reduce the area the force acts on
how to reduce pressure
decrease the force or increase the area the force acts
what is a moment
is the turning effect of a force around a fixed point called a pivot
what does the size of a moment depend on
the size of the force applied
the perpendicular distance from the pivot to the line of action of the force
why is less force needed to open a door
pushing it furthest from the hinge than at the side closest to the hinge. to push at the hinge side of the door requires force to be exerted because the distance is shorter
how to calculate a moment
force x distance
how to balance moments
where an object is not turning around a pivot, the total clockwise moment must be exactly balanced by the total-anticlockwise moment. we say that the opposing moments are balanced.
sums of the clockwise moments = sums of anticlockwise moments
how do levers rely on moments
they rely on the principle of moments to acts as ‘force multipliers’. they reduce the effort needed to move the load by increasing the distance over which it is acting.
what is the centre of mass
centre of mass, where an object will balance on. centre of mass in a symmetrical shape is where the axes of symmetry cross
how to find the centre of mass in a regular shape
- drill a small hole in shape and hang it up so that it can still swing without obstruction
- hang a plumb line from the same suspension point. this makes a vertical line directly below.
- drill another hole at a different location within the object.
- hang another plumb line to determine the vertical and mark it on
- the point at which the two marked lines cross is the centre of mass
