Answer:
Stephen hawking if his family were scientists
A front is a narrow region between two air masses of different densities.
Answer:
44 N
Explanation:
The electrostatic forces between two charges is given by:

where
k is the Coulomb's constant
q1 and q2 are the two charges
r is their separation
We notice that the force is directly proportional to the charges.
In this problem, initially we have a force of
F = 22 N
on a q2 = 4.0 C, exerted by a charge q1.
If the charge is doubled,
q2 = 8.0 C
This means that the force will also double, so it will be

The coefficient of static friction between the chair and the floor is 0.67
Explanation:
Given:
Weight of the chair = 25kg
Force = 165 N (F_applied)
Force = 127 N (F_max)
To find: Coefficient of static friction
The “coefficient of static friction” between a chair and the floor is defined as the ration of maximum force to the normal force acting on the chair
μ_s=
The F_n is equal to the weight multiplied by its gravity
∴
=mg
Thus the coefficient of static friction changes as
μ_s=
μ_{s} = 
= 0.67
Answer:
Explanation:
Given
Initial reading on scale =40 N
So, we can conclude that weight of the sack is 40 N
After this a 10 N force is applied upward on the sack such that the net force becomes (40-10) N downward (because downward force is more)
This net downward force is the resultant of earth graviational pull and the applied upward force.
So, this downward force acts on the machine which inturn applies an upaward force of same magnitude called Normal reaction.
This situation can be diagramatically represented by figure given below