This group is called “noble gases” because they do not react with other elements. This is because they have a full valence shell.
As we know that two charges exert force on each other when they are placed near to each other
The force between two charges is given as

here we know that
= two different point charges
r = distance between two point charges
also we know that two similar charges always repel each other while two opposite charges always attract each other
so here correct answer would be
<em>A. A positive and negative charge attract each other.</em>
Answer:
Explanation:
A Spring stretches / compresses when force is applied on them and they are governed by the Hookes Law which states that the force required to stretch or compress a spring is directly proportional to the distance it is stretched.

F is the force applied and x is the elongation of the spring
k is the spring constant.
negative sign indicates the change in direction from equilibrium position.
In the given question, we dont have force but we know that the pan is hanging. We also know from the Newton's second law of motion that

Inserting this into Hooke's Law

computing it for x,

This is the model which will tell the length of the spring against change in the mass located in the pan.
Answer:
a) v = 6.43 m/s
b) v = 15.8 m/s
Explanation:
Speed of car = 56 km/h
56 km/h = 14.4 m/s
Angle rain makes on the glass to the vertical = 66°
Thus knowing that the opposite side of the angle is the distance moved by the car, and the adjacent side is the distance traveled by the rain in the same time
both of which are directly proportional to their velocities
Then
tan(66°) = 14.44m/s ÷ x
or x = 14.44/tan(66°)
Which is the vertical raindrop velocity of the relative to earth
v = 6.43 m/s vertically towards earth
For v relative to the car is we have vector sum of both velocities
v = √(14.44^2 + 6.43^2) = 15.8 m/s which is the velocity relative to car
= 15.8 m/s