energy

Question 1

definition of energy

Answer 1

the ability to do work

Question 2

define kinetic energy store

Answer 2

energy within movin objects

Question 3

gravitaional potential store

Answer 3

energy due to the position of objects in a gravitational field

Question 4

5 modes of energy transfer

Answer 4

mechanically, heating, electrically, by propagation of magnetic waves, by propagation pf machanical waves

Question 5

mechanical mode of energy transfer

mechanically (by force acting over a distance)

Answer 5

• object pushed by an applied force
• force accelerates object by Newton’s second law
• mechanical work is done by force
• work done us transferred to kinetic store

overall, work done by force transfers to kinetic store of object

Question 6

Heating mode of energy transfer

Heating (due to temp diff)

Answer 6

• cooler object is placed in contact with warmer object
• warmer object transfers energy hy heating to the cooler object due to temp diff

overall, internal store of warmer object to internal store of cooler object

Question 7

elctrical mode of energy transfer

electrically (by electric current)

Answer 7

• battery placed in a closed circuit w light bulb
• energy in chemical potential store of battery allows for flow of electrical current
• electrical current allows for conversion of chemical potential energy into light and infared waves

overall, chemical potential store of battery to light and infared waves

Question 8

define propagation of electromagnetic waves

Answer 8

• sun has thermal energy in its internal store
• energy from sun is transferred to objects by electromagnetic radiation
• objects gain energy in its internal store

overall, internal store of sun to internal store of objects

Question 9

define energy transfer by propagation of mechanical waves

Answer 9

• struck objects vibrate and produce mechanical sound waves
• sound waves transfer energy to eardrums
• eardrums gain energy in kinetic store and vibrate

overall, kinetic store of struck object to kinetic store of eardrums

Question 10

formula for calculating energy in kinetic store

Answer 10

E = 1/2mv^2

E = energy in kinetic store (in J)
m = mass (in kg)
v = speed (in m/s)

Question 11

fomula for calculating energy in gravitational potential store

Answer 11

E = mgh

E = energy in gravitational potential store (in J)
m = mass (in kg)
g = gravitational field strength (in N/kg)
h = height above reference point (in m)

Question 12

principle of conservation of energy

Answer 12

the principle of conservation of energy states that energy cannot be created or destroyed, but only transferred from one store to another. the total energy of an isolated system remains constant

Question 13

application of conservation of energy (formula)

Answer 13

by conservation of energy,

Ep = Ek
mgh = 1/2mv^2
(10)(10) = 1/2v^2 (cancel m out)
v = 14.1 m/s

Ep is energy in potential store
Ek is energy in kinetic store