Answer:

Explanation:
Let the distance from spotlight to wall be 15m, and distance from the man to the building be
.
#Therefore the height of the shadow as a function of the above is 
Hence, height of the shadow is expressed as s=(15-x)m
#See attached photo for illustration
Answer: 55.52 *10^-6 C= 55.52 μC
Explanation: In order to solve this question we have to take into account the following expressions:
potential energy stired in a capacitor is given by:
U=Q^2/(2*C) where Q and C are the charge and capacitance of the capacitor.
then we have:
Q^2= 2*C*U=
C=εo*A/d where A and d are the area and separation of the parallel plates capacitor
Q^2=2*εo*A*U/d=2*8.85*10^-12*1.9*10^-5*11*10^3/(1.2*10^-3)=
=55.52 *10^-6C
Substract two consecutive terms of the sequence to see if there is a common difference:

As we can see, there is a common difference of -6.
Then, if a number of the sequence is given, the next one can be found by adding -6 (which is the same as subtracting 6).
Notice that the first term of the sequence is 3.
Then, the rule for the sequence is to start with 3 and add -6 repeatedly.
Therefore, the correct choice is option A) Start with 3 and add -6 repeatedly.
Answer:
Lifting force, F = 21240 N
Explanation:
It is given that,
Mass of the helicopter, m = 1800 kg
It rises with an upward acceleration of 2 m/s². We need to find the lifting force supplied by its rotating blades. It is given by :
F = mg + ma
Where
mg is its weight
and "ma" is an additional acceleration when it is moving upwards.
So, 
F = 21240 N
So, the lifting force supplied by its rotating blades is 21240 N. Hence, this is the required solution.