Answer:F=4F
Explanation: Columbs law states that The force between the two point charges is directly proportional to the product of charges and inversely proportional to the square of distance between them
Force between the two charges is given by
F=K*q1*q2/r^2
if one charge become 4 times, new force is,
F=4(K*q1*q2)/r^2
F=4F
Where q1 and q2 are the point charges
r is the distance between the two charges
K is a constant of proportion called electrostatic force
Answer: 25.38 m/s
Explanation:
We have a straight line where the car travels a total distance
, which is divided into two segments
:
(1)
Where 
On the other hand, we know speed is defined as:
(2)
Where
is the time, which can be isolated from (2):
(3)
Now, for the first segment
the car has a speed
, using equation (3):
(4)
(5)
(6) This is the time it takes to travel the first segment
For the second segment
the car has a speed
, hence:
(7)
(8)
(9) This is the time it takes to travel the secons segment
Having these values we can calculate the car's average speed
:
(10)
(11)
Finally:
Answer:Theoretical Discussion
The diffraction of classical waves refers to the phenomenon wherein the waves encounter an obstacle that fragments the wave into components that interfere with one another. Interference simply means that the wave fronts add together to make a new wave which can be significantly different than the original wave. For example, a pair of sine waves having the same amplitude, but being 180◦ out of phase will sum to zero, since everywhere one is positive, the other is negative by an equal amount.
Answer:

negative sign indicates that the distance is decreasing with time
Explanation:
Let at any time t after noon that is 12 p.m.
distance traveled by car A = 40t
distance traveled by car B = 90-60t
then distance between the two cars at time t
............1
also, at time 1 p.m.
distance 
D=50 Km
differentiating equation 1 w.r.t. t we get

put t= 1 and D= 50 we get

