Physics
Content
Submarine
a. ) freezing point must be low=because the temperature is low
b.) material must be be strong=to withstand pressure
c.) corrosion rate must be low=as sea water is a good corrosive agent
d.) size of the ballast tank must be large=to enable the submarine to submerge deeper into sea
e.) use thick wall=because water pressure increase with depth
f.) must be made up of high density material=so that it can submerge easily
g.) must be made up of strong material=so that the submarine wont crack easily
h.) must be in aerodynamic shape=so it can reduce the resistance cause by the water
i.) must have ballast tank=so it will increase the overall submarine weight
j.) must have sonar transmitter and receiver=so it can estimate the distance and depth of the
water
Periscope
a.)mirrors are placed at an inclined angle of 45 degree from vertical axis=reflection happens at an
angle of incidence and at an angle of reflection of 45 degree at both the mirrors
b.)dark cardboards can be used to construct the casing of periscope=mirrors are placed in the
casing
c.)cheaper than cctv
To determine the Specific Heat Capacity
a.)use asbestos=good heat insulators
b.) use oil=have a good heat contact with thermometer
c.)use tissue=prevent heat loss
d.)use high power=can increase the temperature faster
Engine of the Rocket
a.)using bigger blades=can increase the air intake
b.)blade must be made of strong material=can withstand strong pressure
c.)increase the number of fuel injectors=more fuel to be burnt to produce greater thrust
d.)increase the size of combustion chambers=more space for fuel to be burnt
e.)decrease the diameter of the nozzle=exhaust gas ejected at higher momentum
Coolant Liquid
a.)high specific latent heat of vapourization=rate of heat removed is faster
b.)low boiling point=easily can vapour
c.)low specific heat capacity=can be cool down faster
Torchlight
a.)use concave mirror=reflected ray is converging
b.)bulb at principal focus=reflected ray can form a parallel beam
c.)batteries connected in series=produces large current
d.) use copper connecting wire=low resistance/large current
Magnifying Glass
a.)use convex lens=magnified image can be obtained
b.)percentage of light pf the lenses must be high=image would be brighter and clearer
c.)focal length should be short=power of lens will be high and can be focused at shorter distance
d.)diameter of lens should be large=can gives a better display
Lift
a.)must use effective hydraulic system and smooth pulley system=can produce large force to pull
the cable that are attached to lift
b.)use thick and strong cables=able to withstand large pulling force and meet safety requirements
c.)effective bracking system=enable the lift to stop in shorter time
d.)electronic warning system=to warn the passengers
e.)large room space in lift=to cater for more people in the lift
Mobile Platform
a.)use materials that can be obtained easily such as steel rod and canvas=to reduce cost
b.)the rods are t-shaped=are equally strong although they are not so heavy
c.)using rods made from lower density=not so heavy
d.)rods can resist rust=can be used in water
e.)rods have sharp ends with smaller surface area=can be planted to ground easily
f.)resistance to heat=can withstand high temperature..
Mini Auditorium
a.)speakers placed at the end of the hall=to drive more nodes
b.)chairs must arrange in tha antinode lines=can listen to stronger sounds
c.)auditorium must be in parabolic shape=reflection to one sound atone point
d.)for ceiling use plasters=to minimize revibration
e.)use carpets=to minimize revibration
Hair Dryer
a.)use soft iron core =can increase the strength of magnet so that the speed of the fan motor will
increase
b.)increase the speed of motor by changing the knob =to increase the number of turns of coil
c.)use thicker coil of wire and shorter wire=to reduce the heating element of the hair dryer
d.)use bigger wire=to reduce resistance
e.)use a higher number of coils for heating element=to increase the efficiency of heat loss so that
can release more heat
Moving Coil Galvanometer
a.)increase the strength of the radial magnetic field=this can increase the force between the
current carrying coil and magnetic field
b.)using hairspring of lower stiffness=smaller opposing forces to stop the turning of the coil
c.)using a lighter pointer=smaller inertia;easier to move
d.)using a coil of lighter mass=smaller inertia;easier to move
e.)increasing the area of the coil=more changes to the magnetic flux,a bigger force produced
Handphone Charger
a.)use laminated soft iron core=so can reduce power loss due to eddy current in core
b.)full-wave rectification=less power loss and continuous power
Gong
a.)size of the hammer is big=so that the surface area that is in contact is big
b.)larger distance between hammer and gong=so that the force applied on the gong is greater
c.)number of turns of the coil is greater=strength of the magnetism is greater
d.)high cuvature of gong=area of air molecule vibrate is greater.
Vacuum Cleaner
a.)use a larger fan driven by a more powerful electric motor=so it can increase the amount and
speed of airflows into the vacuum cleaner
b.)the inlet opening for pumping air and dust into the vacuum cleaner is made narrower=to create
a much lower air pressure region near the inlet opening
c.)using a very large filter to block dust particles while allowing air molecules to pass through=so
can have lots of surface area
d.)larger space for depositing and collecting the dust particles=to ensure that the airflow through
the filter is not blocked by too many dust particles
e.)shorter path for the cleaned air to flow out of the cleaner and return to room=to ensure that
the vacuum cleaner work efficiently so that it can clean the air faster
Bungee Cable
a.)the cable must be elastic=so that the conversion energy can take place
b.)force constant of the cable must be large=so that the extension of the cable will not be too
much
c.)if the force constant is low=the cable may not be able to with stand the force applied.
a. ) freezing point must be low=because the temperature is low
b.) material must be be strong=to withstand pressure
c.) corrosion rate must be low=as sea water is a good corrosive agent
d.) size of the ballast tank must be large=to enable the submarine to submerge deeper into sea
e.) use thick wall=because water pressure increase with depth
f.) must be made up of high density material=so that it can submerge easily
g.) must be made up of strong material=so that the submarine wont crack easily
h.) must be in aerodynamic shape=so it can reduce the resistance cause by the water
i.) must have ballast tank=so it will increase the overall submarine weight
j.) must have sonar transmitter and receiver=so it can estimate the distance and depth of the
water
Periscope
a.)mirrors are placed at an inclined angle of 45 degree from vertical axis=reflection happens at an
angle of incidence and at an angle of reflection of 45 degree at both the mirrors
b.)dark cardboards can be used to construct the casing of periscope=mirrors are placed in the
casing
c.)cheaper than cctv
To determine the Specific Heat Capacity
a.)use asbestos=good heat insulators
b.) use oil=have a good heat contact with thermometer
c.)use tissue=prevent heat loss
d.)use high power=can increase the temperature faster
Engine of the Rocket
a.)using bigger blades=can increase the air intake
b.)blade must be made of strong material=can withstand strong pressure
c.)increase the number of fuel injectors=more fuel to be burnt to produce greater thrust
d.)increase the size of combustion chambers=more space for fuel to be burnt
e.)decrease the diameter of the nozzle=exhaust gas ejected at higher momentum
Coolant Liquid
a.)high specific latent heat of vapourization=rate of heat removed is faster
b.)low boiling point=easily can vapour
c.)low specific heat capacity=can be cool down faster
Torchlight
a.)use concave mirror=reflected ray is converging
b.)bulb at principal focus=reflected ray can form a parallel beam
c.)batteries connected in series=produces large current
d.) use copper connecting wire=low resistance/large current
Magnifying Glass
a.)use convex lens=magnified image can be obtained
b.)percentage of light pf the lenses must be high=image would be brighter and clearer
c.)focal length should be short=power of lens will be high and can be focused at shorter distance
d.)diameter of lens should be large=can gives a better display
Lift
a.)must use effective hydraulic system and smooth pulley system=can produce large force to pull
the cable that are attached to lift
b.)use thick and strong cables=able to withstand large pulling force and meet safety requirements
c.)effective bracking system=enable the lift to stop in shorter time
d.)electronic warning system=to warn the passengers
e.)large room space in lift=to cater for more people in the lift
Mobile Platform
a.)use materials that can be obtained easily such as steel rod and canvas=to reduce cost
b.)the rods are t-shaped=are equally strong although they are not so heavy
c.)using rods made from lower density=not so heavy
d.)rods can resist rust=can be used in water
e.)rods have sharp ends with smaller surface area=can be planted to ground easily
f.)resistance to heat=can withstand high temperature..
Mini Auditorium
a.)speakers placed at the end of the hall=to drive more nodes
b.)chairs must arrange in tha antinode lines=can listen to stronger sounds
c.)auditorium must be in parabolic shape=reflection to one sound atone point
d.)for ceiling use plasters=to minimize revibration
e.)use carpets=to minimize revibration
Hair Dryer
a.)use soft iron core =can increase the strength of magnet so that the speed of the fan motor will
increase
b.)increase the speed of motor by changing the knob =to increase the number of turns of coil
c.)use thicker coil of wire and shorter wire=to reduce the heating element of the hair dryer
d.)use bigger wire=to reduce resistance
e.)use a higher number of coils for heating element=to increase the efficiency of heat loss so that
can release more heat
Moving Coil Galvanometer
a.)increase the strength of the radial magnetic field=this can increase the force between the
current carrying coil and magnetic field
b.)using hairspring of lower stiffness=smaller opposing forces to stop the turning of the coil
c.)using a lighter pointer=smaller inertia;easier to move
d.)using a coil of lighter mass=smaller inertia;easier to move
e.)increasing the area of the coil=more changes to the magnetic flux,a bigger force produced
Handphone Charger
a.)use laminated soft iron core=so can reduce power loss due to eddy current in core
b.)full-wave rectification=less power loss and continuous power
Gong
a.)size of the hammer is big=so that the surface area that is in contact is big
b.)larger distance between hammer and gong=so that the force applied on the gong is greater
c.)number of turns of the coil is greater=strength of the magnetism is greater
d.)high cuvature of gong=area of air molecule vibrate is greater.
Vacuum Cleaner
a.)use a larger fan driven by a more powerful electric motor=so it can increase the amount and
speed of airflows into the vacuum cleaner
b.)the inlet opening for pumping air and dust into the vacuum cleaner is made narrower=to create
a much lower air pressure region near the inlet opening
c.)using a very large filter to block dust particles while allowing air molecules to pass through=so
can have lots of surface area
d.)larger space for depositing and collecting the dust particles=to ensure that the airflow through
the filter is not blocked by too many dust particles
e.)shorter path for the cleaned air to flow out of the cleaner and return to room=to ensure that
the vacuum cleaner work efficiently so that it can clean the air faster
Bungee Cable
a.)the cable must be elastic=so that the conversion energy can take place
b.)force constant of the cable must be large=so that the extension of the cable will not be too
much
c.)if the force constant is low=the cable may not be able to with stand the force applied.
