Zusammenfassung der Ressource
Physics Topic 1-
Motion and Forces
- Vector Quantities
- Vector
quantities
have both
magnitude
and an
associated
direction
- Examples
of vector
quantities
- Force
- Weight
- Displacement
- Velocity
- Acceleration
- Momentum
- Motion
- Speed= Distance/ Time
- Speed measurement practicals
- Ruler and stopwatch- Ruler
measures distance travelled,
stopwatch measures time taken
- Light gates- Size of object measured
with ruler, light gate connects to a
timer which gives the reading
- Video analysis- Distance moved
from frame to frame observed on
a ruler in the pictures, time
between frames is known
- Acceleration= change in velocity/ time taken
- (final velocity) squared- (initial velocity)
squared = 2 x acceleration x distance
- An object will only accelerate if
a resultant force acts on it
- Gravitational attraction provides the
centripetal force needed to keep a planet
in orbit around the Sun
- Scalar Quantites
- Scalar
quantities
only have
a
magnitude
or
size
- Examples
of scalar
quantities
- Temperature
- Mass
- Energy
- Distance
- Speed
- Density
- Newtons Laws
- First law of motion- an object remains in
the same state of motion unless a
resultant force acts on it
- If the forces acting on an
object are balanced, the
resultant force is zero
- Second law of motion-
resultant force= mass x
acceleration
- The ratio of force over acceleration is
called inertial mass. Inertial mass is a
measure of how difficult it is to
change the velocity of an object
- Practical
- Third law of motion- every action
has an equal or opposite reaction
- Weight= mass x gravitational field strength
- Momentum
- Momentum = mass x velocity
- In a closed system (not affected by external
forces) total momentum before an event =
total momentum after an event
- Force= change in momentum/ time taken
- Motion of Vehicles
- Stopping distance= thinking distance+
breaking distance
- Reaction time- ruler drop test
- When a force is applied to the breaks of a
vehicle, there is work done by the friction
between the breaks and the wheel. This
reduces the kinetic energy of the vehicle.
- Kinetic energy = 0.5 x mass x
(velocity) squared
- Work Done= Kinetic Energy