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))
Answers is F=7.84 N
Friction force resists the effect of horizontal force and trying to approch to a limiting force.
we have formula for limiting friction force between block and floor
F=Ц N
where N=mg
putting values we get answer.
Answer:
Work cause a change in kinetic energy
Answer:
Moment of inertia of the system is 289.088 kg.m^2
Explanation:
Given:
Mass of the platform which is a uniform disk = 129 kg
Radius of the disk rotating about vertical axis = 1.61 m
Mass of the person standing on platform = 65.7 kg
Distance from the center of platform = 1.07 m
Mass of the dog on the platform = 27.3 kg
Distance from center of platform = 1.31 m
We have to calculate the moment of inertia.
Formula:
MOI of disk = 
Moment of inertia of the person and the dog will be mr^2.
Where m and r are different for both the bodies.
So,
Moment of inertia 
of the system with respect to the axis yy.
⇒ 
⇒ 
⇒ 
⇒ 
The moment of inertia of the system is 289.088 kg.m^2
