Answer:
A high pitch sound corresponds to a high frequency sound wave and a low pitch sound corresponds to a low frequency sound wave. I hope I got it correct !!
So impulse is a change in momentum.
Mass*(final velocity - initial velocity)
I dont think you will be able to find the average force with the given info because you need to know the time it takes for the car to slow down.
Answer:
a

b

Explanation:
From the question we are told that
The mass of the rock is 
The length of the small object from the rock is 
The length of the small object from the branch 
An image representing this lever set-up is shown on the first uploaded image
Here the small object acts as a fulcrum
The force exerted by the weight of the rock is mathematically evaluated as

substituting values


So at equilibrium the sum of the moment about the fulcrum is mathematically represented as

Here
is very small so
and 
Hence

=> 
substituting values


The mechanical advantage is mathematically evaluated as

substituting values


Answer:
Today, scientists believe that the main reason the earth has had periodic ages is that the climate of earth is controlled by the difference in heating of it's surface by the sun. As for example, the equatorial regions are the warmest as the sun is vertically overhead of those areas and the polar regions where the sun is at the extreme angels are the coldest ones.
Explanation: