Answer:
(a): 
(b): 
Explanation:
<u>Given:</u>
- Charge on one sphere,

- Charge on second sphere,

- Separation between the spheres,

Part (a):
According to Coulomb's law, the magnitude of the electrostatic force of interaction between two static point charges is given by

where,
k is called the Coulomb's constant, whose value is 
From Newton's third law of motion, both the spheres experience same force.
Therefore, the magnitude of the force that each sphere experiences is given by

The negative sign shows that the force is attractive in nature.
Part (b):
The spheres are identical in size. When the spheres are brought in contact with each other then the charge on both the spheres redistributes in such a way that the net charge on both the spheres distributed equally on both.
Total charge on both the spheres, 
The new charges on both the spheres are equal and given by

The magnitude of the force that each sphere now experiences is given by
(a) Intensity obeys inverse square law from basis of light passing through a given surface.
(b) Gravitation obeys inverse square law from the basis of force between two masses.
(c) The maximum magnitude of the acceleration of the block is 126.75 m/s².
<h3>
What is intensity?</h3>
Intensity is the ratio is ratio of power to area of a given surface.
I = P/A (W/m²)
where;
<h3>Universal gravitation law</h3>

Intensity and gravitation do not obey inverse square law for same reason;
- Intensity obeys inverse square law from basis of light passing through a given surface.
- Gravitation obeys inverse square law from the basis of force between two masses.
<h3>Acceleration of the block</h3>
a = v²/A
a = (3.9²)/0.12
a = 126.75 m/s²
Learn more about acceleration here: brainly.com/question/605631
#SPJ1
Answer:
0.75
Explanation:
Since the static frictional force is the maximum force applied just before sliding, our frictional force, F is 300 N.
Since F = μN where μ = coefficient of static friction and N = normal force = 400 N (which is the downward force applied against the surface).
So, μ = F/N
= 300 N/400 N
= 3/4
= 0.75
So, the coefficient of static friction μ = 0.75
Answer:
The bit take to reach its maximum speed of 8,42 x10^4 rad/s in an amount of 1.097 seconds.
Explanation:
ω1= 1.72x10^4 rad/sec
ω2= 5.42x10^4 rad/sec
ωmax= 8.42x10^4 rad/sec
θ= 1.72x10^4 rad

α=7.67 x10^4 rad/sec²
t= ωmax / α
t= 8.42 x10^4 rad/sec / 7.67 x10^4 rad/sec²
t=1.097 sec
I can confirm it is not b.