P9/10 : Motion and Braking Flashcards
what is a moment? and equn?
turning effect of force about a point
M= FD
How do u increase the moment?
- increase perpendicular distance of pivot
- increase size of force
priniciple of momemts ?
total anticlockwise moment=total clockwise moment
what is a lever and how can u make them work better?
A solid bar turning on a pivot
works better if:
- increase size of force
- increase distance of force from pivot
what do GEARS do ?
multiply effect of turning force using moments
why is the moment of each gear NOT the same?
bc it depends on the SIZE of the gear - distance from pivot is larger in larger gear
what is compression, stretching and bending?
COMPRESSION : forces act towards eachother
STRETCHING : forces are away from eachother due to NEWTONS THIRD LAW
BENDING : forces act towards eachother, but at different points on the object
what is hooke’s law? eqn?
extension of object is directly proportional to force applied
f= ke
what is diplacement?
measure of how far somethng is from starting position, along with its direction
what is speed of walking, sound, running, cycling?
1.5m/s
330m/s
3m/s
6m/s
how do lightgates work?
a flag on top of moving object blocks a beam of light - triggers TIMER
- second light gate used to stop timer as it passes through it
timer measures how long light was blocked for
distance is given by length of flag
why is velocity changing in a circular motion?
speed is constant , but direction is changing
what equn links acceleration and velocity?
acceleration = velocity/time
equn for resultant force?
mass x acceleration
define
stopping distance? and equn?
total distance travelled during the time for a car to stop in response to some emergency
stopping d. = thinking d. + braking d.
define
thinking distance? equn?
distance travelled by a car when driver realised they need to brake to when they apply the brakes
thinking d. = speed of car x driver’s reaction time
factors effecting thinking distance?
- tiredness
- distraction
- intoxication
define
braking distance? and factors effecting this?
distance travelled by car under braking force
factor effecting this:
- vehicle condition
- road condition
- vehicle mass
work done by brakes equn?
braking FORCE x braking DISTANCE = 1/2 mv^2
braking d. is propertional to vehicle’s speed
momentum of object equn?
momentum = mass x velocity
p = mv
conservation fo momentum principle?
in a closed system, the total momentum before an event is equal to the total momentum after the event
How do protective pads help reduce injury when player collide?
- increase time for players to stop
- so rate of change of momentum is decreased
- decreasing force exerted
f=m/t
