Answer:
a) ΔL/L = F / (E A), b) 
= L (1 + L F /(EA) )
Explanation:
Let's write the formula for Young's module
E = P / (ΔL / L)
Let's rewrite the formula, to have the pressure alone
P = E ΔL / L
The pressure is defined as
P = F / A
Let's replace
F / A = E ΔL / L
F = E A ΔL / L
ΔL / L = F / (E A)
b) To calculate the elongation we must have the variation of the length, so the length of the bar must be a fact. Let's clear
ΔL = L [F / EA]
-L = L (F / EA)
= L + L (F / EA)
= L (1 + L (F / EA))
The boat is initially at equilibrium since it seems to start off at a constant speed of 5.5 m/s. If the wind applies a force of 950 N, then it is applying an acceleration <em>a</em> of
950 N = (2300 kg) <em>a</em>
<em>a</em> = (950 N) / (2300 kg)
<em>a</em> ≈ 0.413 m/s²
Take east to be positive and west to be negative, so that the boat has an initial velocity of -5.5 m/s. Then after 11.5 s, the boat will attain a velocity of
<em>v</em> = -5.5 m/s + <em>a</em> (11.5 s)
<em>v</em> = -0.75 m/s
which means the wind slows the boat down to a velocity of 0.75 m/s westward.
The answer is D.Puck.
♡♡Hope I helped!!! :)♡♡
