Determine the change in the enthalpy of helium, in kJ/kg, as it undergoes a change of state from 100 kPa and 20 oC to 600 kPa an
1 answer:
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Answer:
Explanation:
Given data in question
mean stress = 50 MPa
amplitude stress = 225 MPa
to find out
maximum stress, stress ratio, magnitude of the stress range.
solution
we will find first maximum stress and minimum stress
and stress will be sum of (maximum +minimum stress) / 2
so for stress 50 MPa and 225 MPa
=
+
/ 2
50 = +
/ 2 ...........1
and
225 = +
/ 2 ...........2
from eqution 1 and 2 we get maximum and minimum stress
= 275 MPa ............3
and = -175 MPa ............4
In 2nd part we stress ratio is will compute by ratio of equation 3 and 4
we get ratio = /
ratio = -175 / 227
ratio = -0.64
now in 3rd part magnitude will calculate by subtracting maximum stress - minimum stress i.e.
magnitude = -
magnitude = 275 - (-175) = 450 MPa
Answer:
Explanation:
Previous concepts
Angular momentum. If we consider a particle of mass m, with velocity v, moving under the influence of a force F. The angular momentum about point O is defined as the “moment” of the particle’s linear momentum, L, about O. And the correct formula is:
Applying Newton’s second law to the right hand side of the above equation, we have that r ×ma = r ×F =
MO, where MO is the moment of the force F about point O. The equation expressing the rate of change of angular momentum is this one:
MO = H˙ O
Principle of Angular Impulse and Momentum
The equation MO = H˙ O gives us the instantaneous relation between the moment and the time rate of change of angular momentum. Imagine now that the force considered acts on a particle between time t1 and time t2. The equation MO = H˙ O can then be integrated in time to obtain this:
Solution to the problem
For this case we can use the principle of angular impulse and momentum that states "The mass moment of inertia of a gear about its mass center is ".
If we analyze the staritning point we see that the initial velocity can be founded like this:
And if we look the figure attached we can use the point A as a reference to calculate the angular impulse and momentum equation, like this:
And if we integrate the left part and we simplify the right part we have
And if we solve for we got:
