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:
θ = 4.78º
with respect to the vertical or 4.78 to the east - north
Explanation:
This is a velocity compound exercise since it is a vector quantity.
The plane takes a direction, the air blows to the west and the result must be to the north, let's use the Pythagorean theorem to find the speed
v_fly² = v_nort² + v_air²
v_nort² = v_fly² + - v_air²
Let's use trigonometry to find the direction of the plane
sin θ = v_air / v_fly
θ = sin⁻¹ (v_air / v_fly)
let's calculate
θ = sin⁻¹ (10/120)
θ = 4.78º
with respect to the vertical or 4.78 to the north-east
Atmospheric pressure is caused by the weight of the atmosphere pushing down on itself and on the surface below it.
Pressure is defined as the force acting on an object divided by the area upon witch the force is acting.