TOPIC 4 - stopping distances Flashcards
what is thinking distance?
the distance the car travel in the time between the driver noticing the hazard and applying the brakes
what two things affect your thinking distance?
your reaction time
how fast you’re going
what affects your reaction time?
tiredness drugs alcohol old age careless attitude
how does how fast you’re going affect thinking distance?
whatever your reaction time, the faster you’re going, the further you’ll go
what affects your stopping distance?
how fast you’re going
the mass of your vehicle
how good your brakes are
how good the grip is
how does how fast you’re going affect braking distance?
the faster you’re going, the further it takes to stop
how does the mass of your vehicle affect braking distance?
with the same brakes, a heavier vehicle will take longer to stop
a car won’t stop as quickly when it’s full of people and luggage
why does how good your brakes are affect braking distance?
worn or faulty brakes will let you down a lot when you need them in an emergency
how does how good you grip is affect braking distance?
you need friction between your tyres and the road surface in order to be able to stop
what does how good your grip is depend on?
road surface
weather conditions
tyres
how does icy roads or wet roads affect how good your grip is?
there isn’t much friction between the tyres and he road
what is the equation for momentum?
mass X velocity
when does an object have more momentum?
the greater the mass and the greater the velocity of the object
is momentum a vector quantity or not?
momentum is a vector quantity
why is momentum a vector quantity?
it has a size and direction (like velocity, but not speed)
is momentum the same before and after?
yes
what happens to momentum when no external forces act?
momentum is conserved
what causes change in momentum?
forces
what happens when a force acts on an object?
it causes a change in momentum
does a larger force mean a faster or slower change of momentum?
faster change in momentum?
if someone momentum changes vey quickly (like a car crash), what happens to the forces on the body?
they will be very larger and more likely to cause injury
why are cats designed with protective features?
to slow people down over a longer time when they have a crash - the longer it takes for a change in momentum, the smaller the force
what factors affect your total stopping distance?
thinking distance
braking distance
