dynamics Flashcards
(28 cards)
d=vt
distance (m)= speed (ms^-1) time (s)
a=v-u/t
acceleration (ms^-2) = final speed (ms^-1) - initial speed (ms^1) / time (s)
how do you determine distance from a v-t graph
calculate the area under the graph
newton’s 1st law
an object at rest will remain at rest and an object in motion will remain in motion with a constant speed in a straight line unless acted on by an unbalanced force
what is a balanced force
the forces acting on an object are equal in size but in opposite directions
what happens when an unbalanced force acts on an object
it will accelerate
F(un)=ma
unbalanced force (N) = mass (kg) acceleration (ms^-2)
how do you increase acceleration (decrease/increase)
decrease mass OR increase unbalanced force
what is mass
a measure of how much matter there is in a substance
what is weight
the force due to gravity acting on a mass
W=mg
weight (N) = mass (kg) gravitational field strength (N kg^-1)
what is newton’s 3rd law
if object a exerts an action force on object b, object b will exert an equal and opposite reaction force on object a (every action has its equal and opposite reaction)
what is terminal velocity
the constant vertical speed reached by a falling object when the forces acting on it are balanced
define average speed
the total distance travelled divided by the total time taken
define instantaneous speed
the speed of a moving object at any particular instant in time
describe an experiment to measure instantaneous speed
measure the length of a mask on a trolley, then put some textbooks under a ramp to create a slope. line up the light gate and connect it to the timer. the light gate will measure the time it took the mask to pass and then use v=dt to work out the speed
define acceleration
the change in speed of a moving object per second
what does an upwards slope represent on a v-t graph
acceleration
what does a horizontal line represent on a v-t graph
constant speed
what does a downwards slope represent on a v-t graph
deceleration
what is friction
a force that acts in the opposite direction to an objects movement, created by two surfaces rubbing against each other
how can friction be decreased
streamlining the object, decreasing surface area, lubricating surfaces (eg oiling), smoothing surfaces
what would happen to the acceleration of the trolley if the forces remained the same but the mass was doubled
it would half
an astronauts connecting rope snaps and she begins to drift away from her craft. why should she throw her spanner away from the craft?
the reaction force will push her back
