The pressure is
.
Answer: Option A
<u>Explanation:</u>
Pressure defines the force acting per single area. So depending upon the amount of force acting over a given area in the perpendicular direction of the object, the pressure acting on that area will vary.
So the pressure is directly proportionate to the applied force on a particular region and inversely proportionate into the areas of the region. Hence, the unit of pressure is considered as
or Pascal. Pressure can also be termed as the number of air molecules present in a specified closed region. Thus, for the present condition

Thus, by appling the given values in the above equation, we get,
= 
So the pressure is
.
D=-5m
a(gravity)=-9.8m/s^2
vi= 0m/s
t=?
use equation d=vi*t+0.5a*t^2
because vi=0, you can cross out vi*t because anything multiplied by 0= 0
rearrange the equation to say t^2=d/0.5a
t^2= -5/-4.9
t^2=1.02
find the square root...
final answer: t=1s
Refrigerant entering the compressor of a refrigeration system is sub-cooled liquid
The liquid refrigerant is sub-cooled to ensure that only liquid and not the vapour enters the throttling valve. In a refrigeration system, the superheating decreases COP increase refrigerating effect but increasing amount of work done. The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required. Higher COPs equate to higher efficiency, lower energy (power) consumption and thus lower operating costs.
Learn more about sub-cooled here:
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In Burglar alarm, LDR acts an AND gate.
Answer: C
Explanation
The LDR is light dependent resistor. The principle used in the working of LDR is that the resistance is inversely proportional to the intensity of light falling on the diode.
In burglar alarm, LDR diode is combined with an IC 555.
Normally an LED source is made to be incident on the LDR diode with same intensity such that the resistance will be maintained constant.
As the LDR is connected with IC, the voltage will be high when light is falling on the diode.
The IC will give only two output states that is high and low. This confirms that LDR in burglar alarm act as AND gate.
As the thief enters and crosses the LED light, the intensity of the light falling on the diode will decrease leading to decrease in the voltage which will cause the alarm to beep.
Answer:
Scalar quantity is the Physical quantity expresed only by their magnitude.