Answer:
Force = mass × acceleration
Acceleration:

From first Newton's equation of motion:

Change = v - u:

Answer:
The coordinates of the point is (0,0.55).
Explanation:
Given that,
First charge
at origin
Second charge
Second charge at point P = (0,1)
We assume that,
The net electric field between the charges is zero at mid point.
Using formula of electric field







Hence, The coordinates of the point is (0,0.55).
Answer:
The velocity of the star is 0.532 c.
Explanation:
Given that,
Wavelength of observer = 525 nm
Wave length of source = 950 nm
We need to calculate the velocity
If the direction is from observer to star.
From Doppler effect

Put the value into the formula







Negative sign shows the star is moving toward the observer.
Hence, The velocity of the star is 0.532 c.
Answer:
5. Quadruple
Explanation:
The electrostatic force between two charged particles is given by:

where
k is the Coulomb's constant
q1, q2 are the two charges
r is the separation between the charges
If the distance between the charges is reduced to half,

So the new force will be

So, the force will quadruple.