motion & forces Flashcards
Compare scalar v vector.
Scalars only have a magnitude whereas vectors have a magnitude & direction.
What is the speed formula?
S=D/T
What is the acceleration formula?
Acceleration = change in velocity / time
Every second an object falls, its velocity will increase by ___
10 m/s
What does a steep and shallow slope mean on a distance time graph?
Larger speed, smaller speed
What does a line going up out of the x axis and a line going down out of the y axis mean in velocity time graphs?
Increasing velocity, decreasing velocity.
What does a straight line, steep slope, gentle slope and flat line meaning in velocity time graphs?
Constant acceleration, large acceleration or deceleration, small acceleration or deceleration and zero acceleration.
What is the formula for acceleration in a velocity-time graph?
Rise/run
The area under a velocity-time graph represents the…
Displacement (distance travelled).
What were Newton’s 3 laws of motion?
- objects will remain at rest, or move with a constant velocity unless acted on by a resultant force (inertia)
- the acceleration of an object is proportional to the objects mass (f=ma)
- whenever 2 bodies interact, the forces they exert on each other are equal and opposite
What is newton’s 2nd law formula?
Force = mass x acceleration
Because of weight…
- objects stay firmly on the ground
- objects will always fall to the ground
- satellites are kept in orbit
What is the formula for weight?
Weight = mass x acceleration
(always convert g to kg)
What is the method for investigating the relationship between force, mass & acceleration by varying the masses added to trolleys?
- set up clamp stands, light gates, trolleys, pulley, mass, string
- measure mass of trolly with no extra masses added
- start with one 0.1kg hanging on end of string & no masses on trolley
- release trolley from rest & record time it takes to travel between light gates
- add one 0.1kg mass to trolley, repeat
- continue adding masses until they’re used up, recording time & velocity
- calculate acceleration using a = tv-u
What is the centripetal force?
An object in a circle is not in equilibrium as it has a resultant force acting on it.
What’s the centripetal force of:
- car around a roundabout
- earth orbiting the sun
- friction between car tyres & road
- gravitational force
What was Newton’s 3rd law?
For every force there is an equal & opposite reaction.
What is the formula for momentum?
p = mv
The momentum of an object will change if…
- the object accelerates or decelerates
- changes direction
- its mass changes
What is an elastic vs inelastic collision?
Elastic = collide & move in opposite directions
Inelastic = collide & move in the same direction
When objects move in opposite directions they will each have a… velocity but when they move in the same direction they will have a … velocity &…
different
combined
mass
What is the principle of the conservation of energy?
Total momentum before collision = total momentum after
How is inertia defined?
Tendency of an object to continue in its state of rest unless acted upon.
What’s the formula for inertial mass?
m=f/a
Larger inertial masses will experience…
Smaller inertial masses will experience…
A smaller acceleration
A larger acceleration
What’s the formula for stopping distance?
thinking distance + braking distance
What’s the formula for reaction distance?
speed of car x driver’s reaction time
What are the factors affecting thinking distance?
- distractions
- intoxication
What’s the formula for braking distance?
1/2 x m x v^2
——————
braking force
What are the dangers caused by large decelerations?
- brakes overheating
- loss of control & injury
