Answer:
The speed of the rock when it is at height h/4 is 
.
Explanation:
At maximum height the final velocity of the rock is equal to 0. Let u is the initial velocity of the rock. Using the conservation of energy to find it as :
.......(1)
We need to find the speed of the rock when it is at height h/4. Let v' is the speed. Using 3rd equation of motion as :
here a = -g and s = h/4
Using equation (1) :
So, the speed of the rock when it is at height h/4 is . Hence, this is the required solution.
The hot discharge gas from the refrigerant compressor is normally cooled and condensed at high pressure. This is then passed through an 'Expansion' valve which decreases the pressure to a low level causing expansion of the refrigerant liquid.
<span>The liquid partially vapourises causing a 'Joule's/Thompson' refrigeration effect' which decreases temperature of the refrigerant which then passes to an evaporator coil in the air circulation system of the building. </span>
<span>In the evaporator coil, the heat exchange between the cold refrigerant and the warm air of the building, vaporises and heats the refrigerant which returns to the compressor. </span>
<span>The cycle is repeated until the air temperature reaches the thermostat set-point and switches off the system. </span>
<span>As a Heat pump, the hot refrigerant gas is not evaporating and condensing. </span>
<span>From the compressor discharge, the hot gas is by-passing the cooler/condenser unit and the expansion valve and passes directly to the 'evaporator' coils but now, as the heating medium for the air circulation system where it's cooled by the heat exchange between the hot gas and the cooler air in the building and returns to the compressor in a continuous cycle. </span>
<span>A Thermostat in the system starts and stops the compressor motor according to the heat or cool temperature settings.</span>
Answer:
3.0 A Is the correct option
Explanation:
I = V / R
I = 12/ 4
= 3
The correct option is D.
Sound proofing is usually achieved by using materials that absorbed or reduce sounds. Different materials are used in sounding proofing and these differ in their abilities to absorb or reduce sounds. The coefficient of absorption of a material refers to that material ability to absorb sound. The higher the percentage of a material absorption coefficient, the better the material's ability to absorb sound. Thus, in the question given above, the material with 62% absorption coefficient have the greatest ability of the three materials to absorb sound effectively. <span />
