Momentum Flashcards
(17 cards)
what is momentum and what is its unit
momentum is mass times velocity, or velocity equals momentum over mass, and its units are kg meters per second
what is force equal to in terms of momentum
change in momentum over time
in a diagram, where should arrows indicating opposite force act
Directly opposite original arrow
are opposing forces the same or different
always different
when a person walks on the ground, there is a force from the … which pushes the … backward
foot, which pushes the ground backwards
how can seatbelts reduce injuries
- they increase time of impact
- for the same momentum change
- which leads to reduced force
- passenger stays in seat
when answering a momentum question, always
combine masses if they fall together
safety features that reduce risk of injury in a car crash
- air bags
- collapsible steering wheels
- strong door support
- safety glass in windows
Centre of gravity in momentum
Centre of gravity moves to one place, the anticlockwise and clockwise moments must be equal there fore force on one are must increase to keep balance
what unit is the mass in p = mv
kilograms
what is an object doing if momentum is 0
stationary
cannon and cannon ball momentum
backward momentum of cannon = forward momentum of cannon ball
what does force equal in momentum
mass x change in velocity / change in time
three safety features in vehicles
- crumple zones
- seatbelts
- airbags
how do seatbelts help
- stop passenger from colliding with the interior of a vehicle
- stretch slightly increase time for passenger momentum to reach 0
how do airbags help
- deployed at the front
- act as a soft cushion to prevent injury
how do crumple zones help
- designed to the exterior
- at the front and back
- increase time over which vehicle comes to rest, lowering the force
