forces Flashcards
what are the Effects of forces? (5)
starts object to move stops object moving changes direction of moving object rotate object change the speed of an object
Permanent change?
temporary change?
Permanent= plastic temporary= elastic
what is force measured in?
Newtons (newton meter or spring balance)
resultant force?
A simple force that has the same effect as two or more forces acting on an object.
what is force
Pull or push exerted upon an object
3 types of forces for this exam?
contact and non-contact and forces on the same object (balanced/unbalanced)
Name 5 Characteristics of forces acting on the same object (balanced/unbalanced)?
- equal or unequal in size
- same or opposite directions
- two or more
- equal and opposite = cancel
- ACT ON SAME OBJECT
FORCES ON SAME OBJECT:
which force change the state of motion and which doesn’t? (examples)
balanced= state of motion stays same (at rest or constant velocity)
Unbalanced- changes the state of motion(speed change or directional motion change)
Hence what would the net forces be for each?
balanced= zero net force unbalanced = non zero net (RESULTANT)
what are contact forces and give 3 types?
Two bodies in contact with each other
Friction
tension
compression
What is another name for non-contact forces?
Field forces
What are non-contact forces and give 3 types?
forces acting over a distance
gravitational
magnetic
electrostatic
attractive and repulsive?
attractive- gravitational
attractive and repulsive- magnetic and electrostatic
what is mass
amount of matter in an object
what is gravity
force of gravity acting on object to pull it down
another name for gravity
weight
does mass change?
mass stays the same everywhere
why does weight change?
due to the change in gravitational acceleration
why does gravitational acceleration change?
due to change in mass of objects and distance between objects
formula for weight
Weight (N) = mass (kg) x gravitational acceleration (m.s -2)
what type of objects do magnets attract specifically?
ferromagnetic- iron, steel, cobalt, nickel
what is used to find the direction of a magnetic field?
compass
what do opposites and like poles do?
opposites- attract
like poles- repel
what are magnetic field lines
invisible field lines around magnets (occurs in a magnetic field and shows direction)
things to remember when drawing magnetic field lines (4)
pattern
direction
never cross
line touches object
characteristics of magnetic field lines (4)
- N to S outside magnet….S to in N inside the magnet
- Field lines never cross
- 3D magnetic field
- more lines = stronger magnetic field
what is geographical south if earth treated as a magnet
North pole of ‘magnet’
what is static electricity?
caused by build-up of electrical charge on object surface
what is a charged atom
an ION
what do negatively charged objects do?
gain electons
what do positively charged objects do?
donate or lose electrons
why are outside electrons easily donated
not attached to nucleus
how can neutral objects be charged
friction cause transfer of electrons between objects
what do substances on the positive side of series do?
donate electrons
what is the law of conservation of energy
energy cannot be created or destroyed, it is merely transferred between objects
what is the polarisation of charge?
occurs when a positive object is separated from the negative charge in an object s a result of another charged object being brought close ( OBJECT IS STILL NUETRAL)
what is the discharge of charge
discharge of electrons when given a pathway. causes sparks, shock of static electricity.
Purposes of gold leaf electroscope? (2)
- determine IF CHARGED
2. determine the charge
name the 8 components of the electroscope?
brass cap insulation glass window brass rod gold lead grounding terminal brass plate metal case
what happens if a negatively charged object is brought to the electroscope
electrons move down and make both brass plate and gold leaf more negative than positive and repel
what happens if the positive object is brought to the electroscope
electrons attract to object and go to brass cap. brass plate and gold leaf have more positive and repel
what if an object is brought to a positively charged electroscope
if the leaf deflects further it’s positive as more electrons attracted to the brass cap
if a leaf falls down its negative as electrons are repelled to brass plate and positive leaf attracts to it and falls down
what if an object is brought to a negatively charged electroscope
if the leaf deflects further it’s negative as more electrons to brass plate = further defection
if a leaf falls down its positive as electrons are attracted to brass cap and the brass plate has more positive charge + gold leaf is attracted.
what is lightning?
discharge of charge built up In thunder clouds as air water particles rub and electrostatic charge is built up
lightning safety precautions (4)
- dont shelter under trees (strikes highest point)
- dont take bath,shower or wash dishes
- don’t be close to bodies of water
- don’t go under roof without lightning conductor
