P1 Flashcards
What are all the ways in which energy can be stored
Chemical,Kinetic,Gravitational potential,Thermal,Elastic potential,Magnetic,Nuclear,Electrostatic
How does energy get lost
When it is dissipated to the surroundings
If a ball hits the ground will it return to it’s height it was dropped from
No due to it losing energy in the thermal energy store,sound store and going back into gravitational potential energy
What is the equation for work done
W=ForceX distance
Calculate the work done when a person applies a force of 250N to move a box moving it 31M
W=FXS
250X31
7750J
Equation for gravitational potential energy
Delta Ep=mXgx deltah
Calculate the gravitational potential energy gained if a 10kg object is lifted 12m high
Gpe=mxgxh,10x9.8x12=1176
Equation for kinetic energy with mass and velocity
1/2XmassXvelocity
Calculate the kinetic energy stored in a vhicle of mass 500kg moving at a speed of 12m/s
500X12^2/2=36000
What does hooke’s law state
That if you double the force you also double the extension as long as the limit of proportionality hasn’t been reached
How do you calculate energy efficiency
Useful output energy/total input energy
What is the useful energy % if a hairdryer has a total input of 500j and a useful output of 200j
200/500X100=40%
How could you improve the efficiency of a bycicle
Use oil or lubricant in order to reduce friction
What is the equation for power using energy and time
Power=energy/time
A light bulb is on for one hour and uses 144000J of energy,What is the light bulbs power rating
144000/3600s=40w
What is a system
Its the word for a single object/a group of objects
What is the net change in the total energy of a closed system
Zero
Equation for change in thermal energy
Change in thermal energy=massXspecific heat capacityXtemperature change
What practical investigates specific heat capacity
The practical where you use a block of the material and wrap it in an insulating layer before measuring the temperature and then setting the power supply on.Take readings of the temperature during (about 10) and then record your results after turning it off
What are the two equations for power
Power=energy transferred/time
Power=Work done/time
