P1- Energy Flashcards
Name 4 energy stores.
-Thermal
-Kinetic
-Gravitational potential
-Elastic potential
-Chemical
-Magnetic
-Electrostatic
-Nuclear
Describe the energy transfers that occur as a ball to the ground.
A ball dropped from the height is accelerated by gravity. The gravitational force does work.
It causes energy to be transferred from the ball’s gravitational potential energy store to its kinetic energy store.
Give the equation for finding the energy in an objects kinetic energy store.
Eķ= 1/2 m v2
E- kinetic energy (J)
m- mass (kg)
v- (speed)2 (m/s)2
If energy is transferred to an object kinetic energy store, what happens to speed?
The object will move at a constant speed
What’s the equation to find the change in energy in an objects gravitational potential energy store for a change in height?
Ep = mgh
Ep- g.p.e (J)
m- mass (kg)
g- gravitational field strength (N/kg)
h- height (m)
What kind of energy store is energy transferred to when you compress a spring?
Elastic potential energy (J)
What’s the equation for Elastic potential energy?
e.p.e = 0.5 × spring constant × (extension)2
Ee= 1/2 k (e)2
What’s the definition of the specific heat capacity of a material?
Specific heat capacity is a measure of how much energy is needed to raise the temperature of a material and is defined as follows: The specific heat capacity of a substance is the energy required to raise the temperature of of the substance by 1 ∘ C .
Practical
(Investigating s.h.c)
Place the immersion heater into the central hole at the top of the block.
Place the thermometer into the smaller hole and put a couple of drops of oil into the hole to make sure the thermometer is surrounded by hot material.
Fully insulate the block by wrapping it loosely with cotton wool.
Record the temperature of the block.
Connect the heater to the power supply and turn it off after ten minutes.
After ten minutes the temperature will still rise even though the heater has been turned off and then it will begin to cool. Record the highest temperature that it reaches and calculate the temperature rise during the experiment
Give the equation that relates energy transferred and specific heat capacity.
ΔE = mcΔT
ΔE- change in thermal energy (J)
m- mass (kg)
c- specific heat capacity (J/kg°C)
ΔT- temperature change (°C)
State the conservation energy principle.
The principle of energy conservation states that energy is neither created nor destroyed.
Define power
Power is the rate of energy transfer, or the rate of doing work.
Power is measured in watts. One watt= 1 joule of energy transferred per second
Give 2 equations to calculate power:
P = E/t P=W/t
P- power (W).
E- energy transferred (J)
t- time (s)
W- work done (j)
What are the units of power?
Watt (W)
How to reduce unwanted energy transfers:
Lubrication- reduces friction, usually liquids like oil.
Thermal insulation- reduces heat transfer between solid objects, fluids, or gases by introducing a barrier between them.
