The answer to this would inFact be A
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


<span>B. The properties they have</span>
Answer: 26 beats in 2 seconds
Explanation:
The number of beats per second = frequency of tuning fork 1 - frequency of tuning fork 2.
Given :
- frequency of tuning fork 1 = 500Hz
- frequency of tuning fork 2 = 487Hz
Thus,
Beats per second = 500 - 487
= 13 beats per second
Therefore in two(2) seconds, you will have 2 x 13 = 26 seconds.
Applicable linear expansion equation:
ΔL = αΔTL
In which
ΔL = change in length, α = Linear expansion coefficient of steel, ΔT = change in temperature, L = original length
Therefore,
ΔL = 12*10^-6*(18.5-(-3))*1410 = 0.36378 m