The question is incomplete. The complete question is :
A viscoelastic polymer that can be assumed to obey the Boltzmann superposition principle is subjected to the following deformation cycle. At a time, t = 0, a tensile stress of 20 MPa is applied instantaneously and maintained for 100 s. The stress is then removed at a rate of 0.2 MPa s−1 until the polymer is unloaded. If the creep compliance of the material is given by:
J(t) = Jo (1 - exp (-t/to))
Where,
Jo= 3m^2/ GPA
to= 200s
Determine
a) the strain after 100's (before stress is reversed)
b) the residual strain when stress falls to zero.
Answer:
a)-60GPA
b) 0
Explanation:
Given t= 0,
σ = 20Mpa
Change in σ= 0.2Mpas^-1
For creep compliance material,
J(t) = Jo (1 - exp (-t/to))
J(t) = 3 (1 - exp (-0/100))= 3m^2/Gpa
a) t= 100s
E(t)= ΔσJ (t - Jo)
= 0.2 × 3 ( 100 - 200 )
= 0.6 (-100)
= - 60 GPA
Residual strain, σ= 0
E(t)= Jσ (Jo) ∫t (t - Jo) dt
3 × 0 × 200 ∫t (t - Jo) dt
E(t) = 0
Answer:
La resistencia que debe ser conectada en paralelo con una de 20 Ω para hacer una resistencia combinada de 15 Ω tiene un valor de 60 Ω
Explanation:
Las resistencias son aquellos dispositivos en los circuitos eléctricos que suelen emplearse para oponerse al paso de la corriente eléctrica.
Se denomina resistencia resultante o equivalente al valor de la resistencia que se obtiene al considerar un conjunto de ellas.
Cuando tenes resistencias en paralelo la corriente se divide y circula por varios caminos.
La resistencia equivalente de un circuito de resistencias en paralelo es igual al recíproco de la suma de los inversos de las resistencias individuales:
Esto también puede ser expresado como:
Entonces, en este caso sabes:
Reemplazando:
y resolviendo:
se obtiene:
R2=60 Ω
<u><em>La resistencia que debe ser conectada en paralelo con una de 20 Ω para hacer una resistencia combinada de 15 Ω tiene un valor de 60 Ω</em></u>
Answer:
I prefer to have a bottle filled with hot water
Explanation:
I would prefer to have a bottle filled with hot water instead of an equal mass of nails at the same temperature, since water has higher specific heat than iron (nails). The higher the specific heat of a substance, the more heat it will emit when cooling down and it will take longer to cool. Therefore, water is the best option.
Answer:
v=3.649 m/s
Explanation:
Lets start with the force of gravity on the elevator.
But the friction clamp opposes this with a force of 17000 N
So the Net force on the elevator is
Kinetic Energy
The motion will be describe
original Kinetic energy + work done = final kinetic energy + spring energy
This effect is explained by increased chain entanglements at higher molecular weights. Increasing the degree of crystallinity of a semicrystalline polymer leads to an enhancement of the tensile strength. Deformation by drawing increases the tensile strength of a semicrystalline polymer.