forces 1 and 2 AUTUMN TEST Flashcards
a vector has…
a scalar has…
magnitude and direction
just magnitude
… cannot be negative but… can
scalars
vectors
examples of scalar
speed
distance
time
mass
energy
examples of vector
velocity displacement acceleration force momentum
what is scalar
can be measured with a number (magnitude)
what is a vector quantity
- measured with a number
- BUT ALSO
- has a direction
gravity-the larger the… the stronger the… the greater the…
mass
field
attraction
weight calc
weight = mass x gravitational field strength
weight is measured using a… by…
force meter/ calibrated spring-balance
by the weighing scales measuring the force you exert then divides by 10 to get the mass
gravitational field strength on earth
9.8
what happens to mass and weight of the same person on two different planets
mass stays the same
e=weight is different bc gfs is different
skydiver example of resultant forces
- initially there is no air resistance so only force acting on him is weight = accelerates
- air resistance increases, resultant force from weight decreases = acceleration decreases
- eventually equal and balance , so no resultant force = no acceleration
work done =
work done = force x distance
elastic deformation
the object returns to its original shape when the load has been removed
plastic deformation
the object does not return to its original shape when the load is removed, this can be a spring when pulled to far
hooke’s law
the extension of an elastic object is directly proportional to the force applied, provided that the limit of proportionality is not exceeded
hooke’s law calc
force = spring constant x extension
F = kx
hooke’s law: why does the graph stop being linear
- the limit of proportionality has been reaches so no longer obeys hooke’s law
- turns to plastic behaviour
hooke’s law: if the graph is just linear with no non linear end section…
.. the material is brittle, so snaps instead of stretching after the elastic limit
work done (spring) calc
work done = 1/2 x spring constant x extension squared
work done on the spring =
= the elastic potential energy stored
if an object is moving in a circular motion, the acceleration… because…
increases because changing velocity is defined as acceleration so the change in direction means it accelerates
speed equation
speed = distance / time
displacement time graphs:
- sharper gradient means…
- negative gradient means…
- horizontal line means…
- curved line means..
sharper gradient = faster speed
negative gradient = returning back to starting point
horizontal line = stationary
curved line = velocity is changing
