Answer:
39.240 W
Explanation:
Let's start by calculating the work done by the engine. We can assume that it is the same work done by the weight of the object to bring it from 40m to the surface: as much energy it takes to bring it up, the same ammount it takes to bring it down. Said work is 
At this point we can simply apply the definition of power, that is
, to get the power of the engine is 
Answer:
=24.25 ^−1
Explanation:
Let and be initial and final velocity of the body respectively,
be acceleration due to gravity ( 9.8^−2 ), ℎ be the height of the body.
=0 ^ −1
ℎ=30
we know that, ^2−^ 2=2ℎ
^2=2∗9.8∗30
^2=588
=24.25 ^−1
Since it was dropped, it should be the speed of gravity which is 9.8 meters/second
Answer:
b. AG, work function=4.74eV
Explanation:
Ultraviolet light starts at the end of the visible light spectrum, where violet light ends:
(wavelength of lowest-energy ultraviolet light)
So, the lowest energy of ultraviolet light can be found by using the formula

where
h is the Planck constant
c is the speed of light
Substituting,

And keeping in mind that

This energy converted into electronvolts is

The work function of a metal is the minimum energy needed to extract a photoelectron from the surface of the metal. Therefore, the metals that exhibit photoelectric effect are the ones whose work function is larger than the energy we found previously, so:
b. AG, work function=4.74eV
Because for all the other metals, visible light will be enough to extract photoelectrons.