P1 - Motion Flashcards
Acceleration
The rate at which velocity changes
Acceleration formula
acceleration = (final velocity-initial velocity) /time
a = (v-u)/t
Deceleration
A decrease in speed
What does a velocity-time graph show?
A velocity-time graph shows how the velocity of a moving object varies with time
- if the object is moving at a constant acceleration/deceleration
- the magnitude of the acceleration / deceleration
Straight line (velocity-time graph)
represents constant speed
Slope of a line (velocity-time graph)
magnitude/rate of the acceleration
Velocity
the speed of an object in a particular direction
Velocity formula
Displacement / time
Steep slope (velocity-time graph)
A steep slope means large acceleration (or deceleration)
Gentle slope (velocity-time graph)
A gentle slope means small acceleration and small change in velocity
Downward slope (velocity-time graph)
decreasing velocity (deceleration)
Horizontal/flat line (velocity-time graph)
A flat line means the acceleration is zero - i.e. the object is moving with a constant velocity
Average speed
total distance / total time
Newton’s first law
Objects in motion tend to stay In motion. Objects at rest tend to stay at rest unless acted upon by an external force
Newton’s second law
The acceleration produced by a net force is directly proportional to the net force and inversely proportional to the mass of the object.
Force = Mass x Acceleration
Newton’s third law
For every action there is an equal and opposite reaction
When object A pushes on object B, object B will exert and equal and opposite force on object A
Centre of Mass
The point at which the mass of an object is thought to be concentrated
Equilibrium
A state of balance (usually between two forces)
Moment
The turning effect of a force about a pivot
Pivot
A fixed point that the object can rotate around
Moment formula
Moment(Nm) = Force(N) x perpendicular distance from pivot(m)
M = Fd
Give 3 examples of moments
- door handle
- wheel barrow
- seesaw
- shovel
- crowbar
Principle of moments
If an object is balanced, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot
What condition must be met for an object to be in equilibrium?
- The forces on the object must be balanced
- There must be no resultant force
- The sum of clockwise moments on the object must equal the sum of anticlockwise moments