Rock is completely immersed in hot water. By the second law of thermodynamics, thermal energy or heat is transferred from substance with higher temperature to substance with lower temperature until they come to thermal equilibrium i.e. both at same temperature.
It is given here that rock is at 20°C which is at lower temperature than water at 80°C. ∴Heat or thermal energy flows from water to rock. So, right choice is-
A. The water gives the rock thermal energy and gets no thermal energy in return.
Answer:
the ratio of the heat rejected to the cold reservoir for the improved engine to that for the original engine is 0.68
Explanation:
Given information
initial efficiency, η
= 0.28
final efficiency, η
= 0.51
ratio of the heat rejected = (1 - η)/(1 - η)
= (1 - 0.51)/(1 - 0.28)
= 0.68
Answer:
at the Equator
Explanation:
The four seasons are determined by four main positions in the Earth's orbit in its turn around the Sun (ecliptic plane), which are called solstices and equinoxes: winter solstice (Capricorn point, December 22), spring equinox (Aries point, around March 21-22), summer solstice (Cancer point, June 21) and autumn equinox (Libra point, around September 22-23).
In the equinoxes, the axis of rotation of the Earth is perpendicular to the sun's rays, which fall vertically over the equator. In solstices, the axis is inclined 23.5º, so that the sun's rays fall vertically on the Tropic of Cancer (summer in the northern hemisphere) or Capricorn (summer in the southern hemisphere).
When falling vertically on Ecuador, it generates a greater impact on the surface of the Tierre reaching a greater amount of energy and therefore UV rays.
Well, the Solar System is made up of planets (the ones that orbit our sun), and moons, comets, stars, asteroids, dust, gas, and minor planets.
<h3><u>Answer;</u></h3>
B. constant acceleration.
<h3><u>Explanation</u>;</h3>
- Free fall is the type of motion of a body or an object when only gravity is acting on it.
- <em><u>All objects undergo free fall on the earth surface at the same rate irrespective of their mass. This is because the gravitational field on the surface of the earth 9.8 N/kg, causes and acceleration equivalent to 9.8 m/s/s of any object in free fall motion.</u></em>
- Therefore,<u> the acceleration of any freely falling object near the surface of the earth is 9.8 m/s².</u>
