When we cook a marshmallow on a metal poker tool over an open flame, there are three ways in which heat energy is transferred: Conduction, convection, and radiation.
<h3>Heat energy transfer</h3>
Heat transfer is the natural transfer of heat from an object with a higher temperature to an object with a lower temperature. Heat transfer can occur in three ways, namely conduction, convection, and radiation.
- Conduction occurs when heat flows from a place with a high temperature to a place with a lower temperature using a fixed heat-conducting medium. Heat transfer from the open flame to the marshmallows via direct fire contact with the marshmallows is an example of conduction.
- Convection is the transfer of heat by means of a stream in which the intermediate substance also moves. If the particles move and cause heat to propagate, convection will occur. The hot air rising from the flames burning the marshmallows is an example of convection.
- Radiation is heat transfer without a medium. Radiation can also usually be accompanied by light. The direct transfer of heat from the flame to the marshmallow in the form of waves is an example of radiation.
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In general,
Power = (energy moved) / (time to move the energy) .
If it's mechanical power, then
Power = (work done) / (time to do the work) .
If it's electrical power, then it can be any one of these:
Power = (volts) x (amperes)
Power = (volts)² / (resistance, ohms)
Power = (amperes)² x (resistance, ohms) .
Whatever kind of energy you're dealing with, power always
turns out to be
(amount of energy produced, used, or moved)
divided by
(time taken to produce, use, or move the energy) .
Explanation:
It is given that,
Initial speed of sprinter, u = 0
Final speed of sprinter, v = 10 m/s
Time taken, t = 1.28 s
a. We need to find the acceleration of sprinter. It can be calculated using first equation of motion as :



b. Final speed of the sprinter, v = 36 km/h
Time, t = 0.000355 h
Acceleration, 

Hence, this is the required solution.
Answer:
Q = 12540 J
Explanation:
It is given that,
Mass of water, m = 50 mL = 50 g
It is heated from 0 degrees Celsius to 60 degrees Celsius.
We need to find the energy required to heat the water. The formula use to find it as follows :

Where c is the specific heat of water, c = 4.18 J/g°C
Put all the values,

So, 12540 J of energy is used to heat the water.