Science chapter 9 Flashcards
REMEMEBR
How do Forces in nature affect us?
Earthquakes, Tsunami, Volcanic Eruption
What can a force be?
A force can be a ‘push’ or a ‘pull’.
How is a force produced?
A force is produced when two objects touch each other or
when our body touches an object.
Forces that are produced
when objects come into contact are called
Contact forces
forces that are produced when objects do not touch each other are called?
Non-Contact Forces
Types of contact forces
Friction and elastic force
Friction is the…
Friction is the force that opposes
motion between two objects in
contact.
Friction allows us to…
Friction allows us to hold on to
things without dropping them.
What and what in our daily lives rely on friction?
walking and writing with a pencil
Elastic force acts on …
a stretched
or compressed elastic object to
return it to its original shape.
Types of non-contact forces?
Gravitational force, electrostatic force and magnetic force
Magnetic force is …
the force exerted by a magnet on
magnetic materials such as iron and steel.
Unlike poles(magnetic)/charges(electrostatic)…and the force is called
attract each other, attraction
like poles(magnetic)/charges(electrostatic)…and the force is called
repel each other, repulsion
Electrostatic force is the…
Electrostatic force is the force of attraction/repulsion
between particles due to their electric charges.
Gravitational force is the…
force of attraction between
objects due to their masses.
What is the gravitational force that the earth exerts on objects.
Our weight
The SI unit of force is ?
Newton (N).
We use a …. to measure force
spring balance
What is mass?
Mass is the amount of matter in a body
SI unit of mass is
Kilogram(kg)
What is weight?
Weight is the gravitational force acting on an object
SI unit of weight is
Newton(N)
How to find weight?
Weight (W) = mass
(m) x gravitational
field strength of the
planet (g)
Gravitational field strength tells us
how strong
The Earth’s gravitational field will
experience a gravitational force
attracting it towards Earth’s centre.
The …
the strength, the … the
gravitational force!
higher, greater
Mass can be measured using a waht or waht
beam balance, electronic
The beam balance compares
the
gravitational force acting on an
object with standard masses.
Mass is … of gravitational field strength
independent
Weight is… on gravitational field strength
dependent
Forces can change the state of
rest or motion of an object
Forces can create what effect on an object
turning
Forces can change the
size and/or shape of an object
Forces can change the pressure on an object
pressure on an object
Speed can be calculated using the formula
speed = dist travelled / time taken
Pressure can be calculated using the formula
pressure = force / area
The what you are in the water, the what the
underwater pressure becomes.
deeper, greater
the air pressure outside our bodies is
… by the air pressure inside our bodies. hence we are not killed by the atmospheric pressure
balanced
The SI unit of energy and work done is
the joule (J).
There is work done when
a force acts on an object and the object moves in the same direction as the force
When work is done,
there will be transfer of energy
from one object to another object.
Work done is calculated using the formula
w = fs
W = work done (in J);
F = force applied (in N);
s = distance moved in the direction of the force (in m).
Types of energy in our daily lives
Potential energy (elastic, gravitational and chemical)
Kinetic energy
Electrical energy
Thermal energy (or heat)
Light energy
Sound energy
Potential energy is the
stored energy in a system.
Types of potential energy
Chemical potential energy
gravitational potential energy
elastic potential energy
Formula to find gravitational potential energy
m g h
m = mass of object
g = gravitational field strength
(= 10 N/kg)
h = height of object
What is kinetic energy?
Kinetic energy is the energy possessed by moving object.
Formula to find kinetic energy
Kinetic energy
= 1/2 m v 2
where
m = mass of object (in kg)
v = speed of object (in m s−1)
Principle of conservation of energy
energy cannot be be created nor destroyed, but
can be converted from one form to another. The
total energy in an isolated system is constant.
An isolated system means that
the objects in the
system only interact with one another and they have
no interaction with any object outside the system.
the total energy in the isolated system
stays
constant
non-renewable sources of energy
are limited and will run out one day
some non-renewable sources of energy are
fossil fuels, diesel, petrol
renewable sources of energy can
be sustained or renewed indefinitely.
can be sustained or renewed indefinitely.
some renewable sources of energy are
solar energy, hydroelectric energy, wind energy, geothermal energy, biofuels and nuclear energy
