Answer:
a) 
Explanation:
a) Let consider that heat pump is reversible, so that the Coefficient of Performance is:



The minimum heat received by the house must be equal to the heat lost to keep the average temperature constant. Hence:

The minimum power supplied to the heat pump is:



Answer:
Option (d) 2 min/veh
Explanation:
Data provided in the question:
Average time required = 60 seconds
Therefore,
The maximum capacity that can be accommodated on the system, μ = 60 veh/hr
Average Arrival rate, λ = 30 vehicles per hour
Now,
The average time spent by the vehicle is given as
⇒ 
thus,
on substituting the respective values, we get
Average time spent by the vehicle = 
or
Average time spent by the vehicle = 
or
Average time spent by the vehicle = 
or
Average time spent by the vehicle =
hr/veh
or
Average time spent by the vehicle =
min/veh
[ 1 hour = 60 minutes]
thus,
Average time spent by the vehicle = 2 min/veh
Hence,
Option (d) 2 min/veh
Answer:
The stress in the rod is 39.11 psi.
Explanation:
The stress due to a pulling force is obtained dividing the pulling force by the the area of the cross section of the rod. The respective area for a cylinder is:

Replacing the diameter the area results:

Therefore the the stress results:

Answer and Explanation:
Commutator are used in DC machine commutator is mainly used for the reversing the direction of the current .It is connected to the armature of the DC generator or motor
ADVANTAGE OF COMMUTATOR The main advantage of the commutator in DC motor is to keep keep the direction of the toque always in the same direction by changing the current direction
DISADVANTAGE OF COMMUTATOR : The main disadvantage is due to the friction between the commutator and brushes there is a friction loss.
The answer is choice C
Explanation:
As during construction ,the site is cleared for all debris before laying out the foundation. Even the sewer lines are dug out .
So it will be useful for the construction crews to connect the pipes to the sewer lines before the foundation is poured.
But usually the steps take in construction activity is:- first the site is cleared for the foundation to be poured and once the foundation wall is set , then all utilities , including plumbing and electrical activities are done.,
After this process is over, the city inspector comes to check whether the foundation has been laid down as per the code of construction.
Only after that the rest of the construction activity follows through.