Answer:
a) The potential energy in the system is greatest at X.
Explanation:
Let be X the point where a ball rests at the top of a hill. By applying the Principle of Energy Conservation, the total energy in the physical system remains constant and gravitational potential energy at the top of the hill is equal to the sum of kinetic energy, a lower gravitational energy and dissipated work due to nonconservative forces (friction, dragging).
Conclusions are showed as follows:
a) The potential energy in the system is greatest at X.
b) The kinetic energy is the lowest at X and Z.
c) Total energy remains constant as the ball moves from X to Y.
Hence, the correct answer is A.
Answer:
over harvesting, pollution, introduction of invasive species such as new predators and food competitors
Explanation:
The main cause of mass extinction is Humans cause extinction of a species through overharvesting. The second main cause is pollution ., introduction of invasive species such as new predators and food competitors, habitat destruction, overhunting and other influences. Another very important cause of mass extinction is the unsustainable human population growth.
The five mass extinction events are
Ordovician Mass Extinction
Devonian Mass Extinction
Permian Mass Extinction
Triassic -Jurassic Mass Extinction
and Cretaceous -Tertiary (or the K-T) Mass Extinction.
Answer:
5.65 times
Explanation:
60 db sound is equal to 60 phons sound when frequency is kept at 1000Hz.
But when the frequency of sound is changed to 100 Hz , according to equal loudness curves , the loudness level on phon scale will be 35 phons.
A decrease of 10 phon on phon- scale makes sound 2 times less loud
Therefore a decrease of 25 phons will make loudness less intense by a factor equal to 2²°⁵ or 5.65 less intense . Therefore intensity at 100 Hz
must be increased 5.65 times so that its intensity matches intensity of 60 dB sound at 1000 Hz frequency.
