Answer:
F1 = k Q1 * Q2 / R^2
If Q1 is doubled then F2 = 2 F1 = 72 units
The time described above is known as the waves Period.
The time which it takes for a particle to complete one full cycle is known as the period. Period is normally measured in seconds. Frequency on the other hand is the number of cycles which are completed in a given period of time e.g a second. periodic time T is given by reciprocal of frequency (1/f).
Reflection. It occurs when a wave bounces from the surface of an obstacle
To solve this problem we will apply the given concept for torque which explains the relationship between the force applied and the distance to a given point. Mathematically this relationship is given as

Where,
Torque
F = Force
d = Distance
Our values are given as,

Therefore replacing we have that the force is

F = 12.72N
Therefore the least amount of force that you must exert is 12.72N
Acceleration is defined as the rate of change of velocity, which, simply put, is a mouthful to describe how fast something speeds up, slows down, or turns. The equation for acceleration is
a = Δv / Δt,
or your final velocity - your starting velocity, then divided by the amount of time. It can also be expressed as
a = (Vf - Vi) / t,
Where Vf is your final velocity, Vi is your initial velocity, and t is the time traveled.
The question gives us that the helicopter moves from a starting velocity of 30 m/s to a final velocity of 40 m/s in the span of 5 seconds. This means we can fill in the variables to the equation, where
Vf = 40,
Vi = 30, and
t = 5.
Plug these known variables into the original equation, and we get
a = (Vf - Vi) / t = (40 - 30) / 5.
From here, the answer comes down to 10 / 5, or 2 m/s^2.
Hope this helps! If you have any questions, don't hesitate to ask :D