A stationary object remains stationary
if the sum of the forces acting upon it -
Resultant Force - is Zero
If the resultant force is not zero
the object will start to accelerate,
in the same direction as the force
The acceleration depends on the force
applied, and the mass of the object
An object may have several different
forces acting upon it, which can have
different strengths and directions.
When all the forces are balanced,
the resultant force is zero. in this
case: a stationary object remains
stationary and a moving object
keeps on moving at the same
speed in the same direction
Force Mass and Acceleration (F = M x A)
Objects accelerate when the
resultant force is not zero and
their are factors including mass
and speed which affect variables
An object will accelerate in the
direction of the resultant force. The
bigger the force, the greater the
acceleration. Doubling the size of
the force, doubles the acceleration
An object will accelerate in the
direction of the resultant force. a
force on a large mass will
accelerate it less than the same
force on a smaller mass. Doubling
the mass halves the acceleration
Forces and Motion
The gradient of a
distance time
graph represents
the speed of an
object
The velocity of an object is its
speed in a particular direction.
The slope on a velocity time
graph represents the
acceleration of an object
When an object moves in a
straight line with a constant
acceleration, you can calculate
its acceleration if you know
how much its velocity changes
and how long this takes
Forces and Breaking
The stopping distance of a car depends
on two factors: - Thinking distance and
breaking distance. Under normal driving
conditions, the thinking and breaking
distance depend on the speed of the car.
When a vehicle travels at a steady speed
the driving force from the engine is balances
by the air resistance and other resistive
forces. The resultant force is zero.
It takes time for a driver to
react to a situation and start
to apply the breaks. The car
carries on moving during this
reaction time.
The thinking distance is the distance travelled
in the reaction time, The thinking distance
increases if the reaction time increases. This
can happen if the driver is: Tired, Distracted,
Under the influence of drugs or alcohol.