Science WA2 Flashcards
What is speed?
Speed is a measure of how fact an object moves and is defined as the distance travelled per unit time
What a force do?
Make a stationary object move
Stop a moving object
Make a moving object speed up or slow down
Change the direction of a moving object
Change the shape and size of an object
Create a turning effect to make an object turn or move
SI Unit for forces
Newton (N)
What can forces be measured by?
by a force meter e.g. spring balance
What are the types of forces and definitions?
Non-contact force
Force that acts between objects that are not touching each other
Contact Force
Force that sits between objects that are touching each other
What is gravitational force?
Gravitational force is a force that exists between objects that have mass
What is the formula of gravitational force
w = mg w:weigh(in N) m:mass(in kg) g: gravitational field strength (in N/kg)
As mass increased, weight on earths surface…
increases
Mass vs weight
Mass is the measure of the amount of matter in an object and depends on the number of particles used to make an object
Weight is the meausre of gravitational force acting on a object
depends on both mass of object and gravitational field strength at location
Si Unit of mass
kg
SI Unit of weight
newton(N)
mass measured by..
electronic balance and beam balance
weight measured by…
extension spring balance, compression spring balance
What is magnetic force
exerts a non contact force known as a magnetic force
What is frictional force
Friction is a force which opposes the movement of an object
When does friction act?
whenever one surface rubs against another surface
What is air resistance
Air resistance is the frictional force experienced by a moving object in the air
Application of friction
prevents us from slipping when we walk
prevents objects from slipping from our hands
allows us to light a matchstick
bad things about friction
causes surfaces to heat up
can wear down objects
can slow down movement
how to overcome friction
applylubraicants between surfaces
use of wheels and ball bearings
make sirfaces smoother
streamlining
What is the state of motion
State of motion simply desciribes how an object is moving
when forces are balance, resultant force is…
zero. objects will continue to be at res tor move with constant speed in a striaght line
effects of resultant force
start a body moving
stop a moving body
change the speed of the body
change direction of body
Pressure
defined as the force applied perpendicular to the surface of an object per unit area
formula of pressure
force/contact area
SI unit of pressure
Pascal (Pa) or newton per square metre (N/msquared)
Factors affecting pressure
Area of contact, force
fluid pressure
pressure in a liquid increases with the depth and density at the liquid with gravitational field strength
what is the turning effect of a force called
pivot
for turning effect to increase
force applied at perpendicular distance furthest away from the pivot
What is energy
energy is the ability to do work
si unit of energy
joule (J)
what is GPE
energy stored due to an object’s height from a reference point in a gravity field
factors affecting GPE
mass of object and vertical height of the object above its reference point and
gravitational field strength acting on object
principle of conservation of energy
energy cannot be created or destroyed
energy can only be converted from one form to another
difference when negligible air resistance
w air resistance + TE when gg up rate of energy production goes down
and when gg down rate of energy production goes up
what is work done
product of a force and the distance moved in the direction of the force
formula of work done
force * distance moved in the directions of the force
si unit of work done
joule (J)
there is NO work done when:
does not move even when force is applied
moves at a constant
speed when there is no force acting on it
moves perpendicular (at a right angle) to the force at a constant speed
application meterorite
renewable energy
energy that is replenished or resupplied faster than being used up
non renewable energy
energy that is used up faster than it can be replenished or resupplied
non renewable forms of energy
fossil fuels, nuclear energy
renewable forms of energy
biofuels, wind, hydropower, geothermal power, solar power
fossil fuels adv/disad
fossil fuels are relatively cheap
does not depend on env. factors
non renewable
will pollute the env as it contributes to greenhouse gases
nuclear energy adv/disad
clean energy with no greenhouse gas emission
non renewable, expensive, time-consuming to build
requires a lot of space and land
biofuels adv/disad
renewable can be produced from the recycling of food waste
requires a lot of space and land
lead to deforestation and habitat loss
burning of biofuels releases greenhouse gases
wind adv/disad
clean, sustainable and abundant
cost effective, nofuel costs
variabke energy source
turbines can be loud and negatively impact local wildlife
hydropwer adv.disad
renewable source of energy
no pollution as no burning of fossil fuels
affects wildlife in the process of construction
hydro electricity dams flood farms and push people from their homes
Geothermal power adv/disad
renewable energy resource
no harmful polluting
most parts of the world do not have suitable areas where it can be exploited
solar power ad/disad
renewable energy source
no harmful polluting
has high initial cost
requires a lot of space
weather dependant
