A vector quantity has both magnitude and direction
Velocity is a vector quantity, measured in m/s
Displacement is a vector
quantity, measured in an
appropriate unit. E.g. metres
Weight and Terminal Velocity
Mass is not the weight of an object, but
measures the inertia an object has, in Kg. Weight
is the mass of an object multiplied by the
gravitational field strength(N/Kg). Weight is
measured in Newtons.
Weight= Mass x Gravitational Field Strength
Forces
To calculate a force, you can use two
equations depending on what values you are
given in the exam question. Force is always
measured in Newtons.
F=ma (Force = Mass x Acceleration)
F=mv-mu / t (Force= Change in
Momentum divided by time taken)
A Resultant Force means that an object is accelerating,. This
means that the forces acting on the object are unbalanced. If
the forces of an object are balanced, then the resultant force
is zero. The diagram shows resultant forces.
When an object falls, it encounters air
resistance while gravity is pulling it down.
The velocity continues to increase until the
force of gravity is balanced with the force
of air resistance. This property is called
Terminal velocity, the velocity at which an
object stops accelerating.
D-T and V-T Time Graphs
D-T (Distance Time Graph
A distance-time graph shows
how far an object travels
over a period of time.
V-T (Velocity Time Graph)
A velocity time graph shows the
change in velocity of an object over
a period of time. A curved line
shows acceleration, whereas a
straight line shows a constant
velocity. The area underneath the
graph can be used to calculate the
distance travelled by the object.
Speed, Velocity and Acceleration
Speed is how fast an object is moving, measured in m/s.
Speed is given by Speed= Distance divided by time taken to cover distance
Acceleration is the rate of change of Velocity,
measured in m/s^2
Acceleration = v-u (change in velocity or
final velocity - initial velocity) / time
taken
Change in velocity is measured in m/s
and time is measured in seconds.