Permafrost is a thick subsurface layer of soil that remains frozen throughout the year, occurring chiefly in polar regions.
I believe it would be D.
Answer:
В. An object with mechanical energy is always able to perform work.
Explanation:
Energy can be defined as the ability (capacity) to do work. The two (2) main types of energy are;
a. Gravitational potential energy (GPE): it is an energy possessed by an object or body due to its position above the earth.
b. Kinetic energy (KE): it is an energy possessed by an object or body due to its motion.
Furthermore, the mechanical energy of a physical object or body is the sum of the potential energy and kinetic energy possessed by the object or body and it is measured in Joules.
Mathematically, it is given by the formula;
Mechanical energy = G.P.E + K.E
Hence, the true statement is that an object with mechanical energy is always able to perform work.
Here object is dropped from height "h"
so we can say its initial speed is zero
and it will accelerate downwards due to gravity
now we can say it will take time T to hit the ground
now we can use
now it is given that it will take 1 second to drop h/2 height to strike the ground
so here we have can say that in "T - 1" s it will cover the h/2 distance from start
now we can say
from above two equations we have
now we can find total height of the drop by first equation
The wavelength will chang along with the frequency, I think. I don't recall why it would lose energy...