Physics: Forces Flashcards
What is a scalar quantity
something that only has magnitude
what is a vector quantity
something that has magnitude and direction
What is a contact force
Force that acts upon multiple objects when they are touching
What is a non contact force
Force that acts upon an object when it isn’t touching another one
What is the weight equation
W (Weight) = m (mass) x g (gravitational field strength)
What is resultant force
The overall force acting on an object or point
What is the resultant force/work done equation
W (work done/resultant force) = F (Force) x s (distance)
What three things can happen to elastic objects that transfers energy
Stretching, Compressing, Bending
What is the elastic force equation
F (Force) = k (spring constant) x e (extension)
What is the Elastic Potential Energy equation
EPE = 0.5 x k (spring constant) x e2 (extension squared)
What is a Moment
Turning effect of a force
What is the moment equation
M (Moment) = F (force) x d (distance)
How do levers work
Levers increase the distance from the pivot at which the force is applied making it easier to do work because less force is required
What is a gear
Gears are circular discs with teeth around their edges that interlock so that turning one causes another to turn, in the opposite direction
Why are gears used
Transmit the rotational effect of a force from one place to another
How do gears work
Increase the distance between the pivot and the force which means a bigger gear can create a bigger moment but turns more slowly
What is the pressure equation
p = F (force) / A (Area)
What is the pressure in a liquid equation
p = h (height of column of liquid) x p (Greek letter rho density) x g (gravitational field strength)
When does an object float
Weight = Upthrust
How does height affect atmospheric pressure
Atmospheric pressure decreases with height
What is the distance equation
s (distance) = v (speed) x t (time)
what is the typical everyday speed of a person walking
1.5 m/s
what is the typical everyday speed of a person running
3 m/s
what is the typical everyday speed of a person cycling
5 m/s
what is the typical everyday speed of a car
25 m/s
what is the typical everyday speed of a train
55 m/s
what is a typical everyday speed of a plane
250 m/s
what is acceleration
How quickly you’re speeding up
what is the acceleration equation
a (acceleration) = /\v (change in velocity) / t (time)
what is the constant acceleration equation
v2 (final velocity squared) - u2 (Initial velocity squared) = 2as (2 x acceleration x distance)
what is the area of a distance time grpah
Speed
what is the area of a velocity time graph
Acceleration
what is terminal velocity
Highest velocity attainable by an object as it falls
What is Newton’s first law
resultant force is needed to make something start moving, speed up or slow down
what is the resultant force equation
F (resultant force) = m (mass) x a (acceleration)
what is inertia
tendency for motion to remain unchanged
what is Newton’s third law
when two objects interact, the forces they exert on each other are equal and opposite
what is the stopping distance equation
stopping distance = thinking distance + breaking distance
What two factors affect thinking distance
speed and reaction time
what three factors affect breaking distance
speed, weather and condition
what does speed affect more breaking distance or thinking distance
breaking distance
what is the momentum equation
p (momentum) = m (mass) x v (velocity)
what is the momentum force equation
F (force) = m/\v (change in momentum) / /\t (change in time)
what three safety features do cars have to change momentum
crumple zones, seat belts stretch, air bags
what safety feature do bike helmets have
contain a crushable layer
