Force and Motion Flashcards
Acceleration:
is the rate of change of speed
Displacement:
is a vector quantity and describes the overall change in position of an object from its original position
Inertia:
Is the object’s resistance to motion
Inertia devices:
Devices used as safety measures against inertia e.g. seat belts, airbags and head rests
Instantaneous speed:
Is the speed of an an object at any particular time
Scalar:
Is a quantity which has magnitude only
Vector:
Is a quantity which has magnitude and direction
Weight force:
Force on any object due to gravity
How do you calculate:
Average velocity=
displacement/ time where: Velocity is in metres/ per second (m/s or m/s-1) Displacement in metres Time in seconds
How do you calculate:
Acceleration=
final velocity- initial velocity/ time taken where: Final velocity (m/s) Initial velocity (m/s) Time (s) Acceleration (m/s/s or m/s2)
For an object to accelerate a force is required. For the same object:
o A bigger force causes a faster acceleration than a smaller force
o A smaller mass will accelerate quickly than a larger mass
Conversion:
m/s -> km/h
X 3.6
Conversion:
km/h -> m/s
Divide 3.6
What are the three types of motion graphs?
- Displacement time graph
- Velocity- time graph
- Acceleration- time graph
Displacement- time graphs:
The slope gives______
object’s average speed/ velocity
Velocity- time graphs:
The slope gives_____
the rate of acceleration
What does the area under a velocity- time graph tell?
The distance travelled by an an object up to that line.
Ticker timer:
A device that measures speed
How many times does a ticker time vibrate per second?
50
What is the time between each dot in a ticker time?
0.02 seconds
Ticker timer:
1) Constant velocity
2) Acceleration
3) Deceleration:
1) dots are evenly spread apart
2) dots become increasingly apart
3) dots become increasingly closer together
Force:
Is a push, pull or twist
How can force change to motion of an object?
o Accelerating objects
o Decelerating objects
o Changing the direction of objects
o Changing the shape of objects
Contact forces:
When there is direct contact between force and object
Friction:
Force acting between two rubbing surfaces
Air resistance/ drag friction
When air (or liquid) moves across an object
Tension:
Force in a straight rope as it pull on an object
Surface tension:
Force between water particles to form a skin/ film on the surface of a liquid
Buoyancy:
Water force acting upwards to keep objects afloat
Lift:
Upward force covered by air moving over an airfoil e.g. wing of a plane
Thrust:
force caused by gases/ liquids being pushed out from a propeller or engine
Non contact force:
Occurs when an object is within a force field
Weight:
gravity pulls object downwards towards the centre of the planet
Electrostatic:
force of charged object, same charges repel each other, whilst opposite attract
Magnetism:
force of magnets where same charges repel whilst opposite attract
Force diagram:
represent the forces acting on an object
- Forces are drawn as line with arrowheads
o Arrow heads represents direction
- Length of arrow represents size
Vector diagram:
allows us to sum the forces acting on an object (net force) and allows us to resolve if it is a balance or an unbalanced force
Newton’s first law of motion:
An object will remain at rest or continue moving at a constant velocity in a straight path unless acted upon by a net unbalanced force
The heavier the object the more inertia it has
The faster the object the more inertia it has
Newton’s second law of motion:
- The acceleration of an object is related to the size of the force acting on the object and the mass of the object
- F=ma
Where:
F= force (N)
m= mass (kg)
a= acceleration (m/s2)
Newton’s third law of motion:
- For every action force , there is an equal and opposite reaction force
- When an object applies a force to another object, the second object applies an equal and opposite force to the first object.
Nuclear potential energy:
Stored in nuclei of atoms and when nuclei split or combined energy is released into other forms
Law of conservation of energy:
Energy cannot be destroyed or created, only transformed or transferred
KE=
1/2 mv^2 Where; m= mass (kg) KE= kinetic energy (J) v= velocity (m/s)
Kinetic energy:
Energy of motion
NOTE:
- the faster the object the more KE it has
- the heavier the object the more KE it has
Gravitational potential energy:
Stored energy as object is lifted. Hence when an object is released GPE will be converted into KE causing it to accelerate to the ground. GPE= mgh m= mass (kg) g= gravity (9.8m/s^2) h= height (m)
Elastic potential energy:
Energy in objects which are stretched or compressed e.g. rubber bands, balls and spring.
EPE is converted into KE
Chemical potential energy:
Energy stood within chemicals. After a chemical reaction takes place, energy is converted into other forms e.g. kinetic, light, heat, electric
Work:
Occurs when a force is applied to an object. With the amount of work done related to the force that has been applied and the distance the object has travelled. W= Fd where: W= work(Nm) F= force (N) d= distance (m)
