Answer:
C. Both technicians A and B
Explanation:
From the physical definition, power is defined as the rate of a body doing work. It is expressed as
P = w/t watts
Where
w - is the work done or the energy of the system in joules
t - time
The unit of power is represented in watts.
Whenever there is a rate of change of energy in the system, it accounts for the efficiency of the power of the system.
Hence, the statements of both technicians are correct.
In a distance time graph, when the x and y values are positive (in first quadrant), the runner is moving forward.
While, if the distance value ( in the y axis) is negative, the runner is moving backwards ( towards the start) .
Hope it helps :)
Answer:
Lithium
Explanation:
The equation for the photoelectric effect is

where
is the energy of the incident photon, with
h being the Planck constant
c is the speed of light
is the wavelength of the photon
is the work function of the metal (the minimum energy needed to extract the photoelectron from the metal)
is the maximum kinetic energy of the emitted photoelectrons
In this problem, we have
is the wavelength of the incident photon
is the maximum kinetic energy of the electrons
First of all we can find the energy of the incident photon

Converting into electronvolts,

So now we can re-arrange the equation of the photoelectric effect to find the work function of the metal

So the metal is most likely Lithium, which has a work function of 2.5 eV.
Explanation:
The nearest star to the Earth is the red dwarf star Proxima Centauri, at a distance of 4.218 light-years.
Light year is the unit of distance covered by the heavenly bodies. 1 light year is equal to :
So,
We need to convert 4.218 light-years barley corns.
Since, 1 barleycorn = 1/3 inch


So, the nearest star to the Earth is at a distance of
. Hence, this is the required solution.
Answer:
According,to the law of conservation of energy,the amount of energy in a closed system always stay constant. ... So,the amount of work output and other transformed energy is equal to the amount of energy inputs. • In this way,the conservation of energy is fulfilled by the machines.