Forces Flashcards
What do forces do to objects?
- change the shape
- change the speed
- change the direction
- change the size
Weight
weight = mass x g
Gravity
(g)
about 10N on Earth
Conservation of Momentum
In an isolated environment, all momentum is conserved → transferred between objects
total momentum before = total momentum after
Acceleration
The resultant force is acting in the same direction as the velocity
Deceleration
The resultant force is acting in the opposite direction to the velocity
Momentum
mass x velocity
p = mv
Newton’s 1st Law
An object will remain at rest or at a constant speed unless acted upon by a resultant force
Newton’s 2nd Law
Resultant force is directly proportional to acceleration
F = ma
Newton’s 3rd Law
If object A exerts a force on object B, then object B will exert a force on object A in equal magnitude in the opposite direction
Scalar Quantity
A physical quantity that has magnitude only
Vector Quantity
A physical quantity that has magnitude and direction
Centripetal Force
The resultant force that produces circlular motion. It always acts towards the centre of the circle and is perpendicular to velocity
Impact Force
change in momentum / time
F = (mv - mu) / t
How do cars decrease impact force?
- crumple zones
- seatbelts
- airbags
these increase the time taken for the change in momentum (cannot decrease change in momentum only time) which decreases the impact force
