8 newton's law of motion Flashcards
friction
force opposing the motion of a surface that moves or tries to move across another surface
weight
the force of gravity acting on an object
W=mg
gradational field strength
force of gravity per unit mass on a small object
9.81
intertia
resistance of an object to change of its motion
terminal speed
the maximum speed reached by an object when the drag force on it is equal and opposite to the force causing the motion of the object
drag force
the force of fluid resistance on an object moving through a fluid
motive force
the force that drives a vehicle
thinking distance
the distance travelled by a vehicle in the time it takes the driver to react
braking distance
the distance travelled by a vehicle in the time taken to stop it
stopping distance
thinking distance + braking distance
newtons second law
F=ma
newtons first law
objects either stay at rest or move with constant velocity unless acted on by a force
resultant force
F1 - F2 = ma
rocket problems
T = mg + ma
pull problems
Mg -mg = (M+m)a
drag force depends on
shape of the object
speed
viscosity of the fluid
impact time
t = 2s/ u+v
impact force
F=ma
vehicle bumpers
lower impact speed- increase the impact time
impact force is reduced
high speed= damage
crumple zones
give way in a front end impact
impact time is increased and impact force reduced
seat belt
slows you down gradually
collapsible steering wheel
if the driver makes contact with the steering wheel, the impact force is lessened as a result of the steering wheel collapsing in the impact
airbags
reduces the force on a person, because the airbag acts a as a cushion and increase the impact time on the person. force of impact is spread over the contact area is pressure is reduced
