topic 2 motion & forces (newtons laws) Flashcards
what is newtons 1st law
an object has a constant velocity unless acted upon by a resultant force
what is newtons 2nd law.
- the acceleration of an object is directly proportional to the resultant (or net) force and inversely proportional to the mass of the object
- resultant force = mass x acceleration
what is newtons 3rd law
every action force has an equal and opposite reaction force
what is an example of newtons 1st law
a ball rolling down a hill will continue to roll unless friction or another force stops it
what is a example of newtons 2nd law
pushing a shopping trolley, it’s easier to push it when it’s empty then when it’s full, more mass requires more acceleration
what is an example of newtons 3rd law
bouncing a ball, when a ball hit the floor the ball applies an action force on the ground, the ground applies a reaction force and the ball bounces back
where is momentum conserved
momentum is conserved in a collision
what is an example of momentum always being conserved in a collision
2 marbles colliding with each other will have momentum before and after the collision
what is human reaction time
there is a delay between a human observing an event and acting upon it
how do you measure human reaction time
ruler drop experiment: someone hold a ruler just above someone’s open hands, they drop it at a random time, record the distance from the bottom of the ruler to the place where it was caught, average this - 1cm is 50ms, 2cm is 60ms, 3cm is 70cm and so on
what is the average human reaction time
0.25 seconds (250 millimetres)
what affects thinking distance
speed, affected by reaction time, concentration, tiredness, distractions, influence of drugs/alcohol
