The Chinese had a toy helicopter some 1000 years ago. True Or False ?
1 answer:
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Answer:
Explanation:
Given that:
The direction of the applied tensile stress =[001]
direction of the slip plane = [01]
normal to the slip plane = [111]
Now, the first thing to do is to calculate the angle between the tensile stress and the slip by using the formula:
where;
= directional indices for tensile stress
= slip direction
replacing their values;
i.e = 0 ,
= 0
= 1 &
= -1 ,
= 0 ,
= 1
Also, to find the angle between the stress [001] & normal slip plane [111]
Then;
replacing their values;
i.e = 0 ,
= 0
= 1 &
= 1 ,
= 1 ,
= 1
However, the critical resolved SS(shear stress) can be computed using the formula:
where;
applied tensile stress 13.9 MPa
∴
Answer:
The net amount of energy change of the air in the room during a 10-min period is 120 KJ.
Explanation:
Given that
Heat loss from room (Q)= 60 KJ/min
Work supplied to the room(W) = 1.2 KW = 1.2 KJ/s
We know that 1 W = 1 J/s
Sign convention for heat and work:
1. If heat is added to the system then it is taken as positive and if heat is rejected from the system then it is taken as negative.
2. If work is done by the system then it is taken as positive and if work is done on the system then it is taken as negative.
So
Q = -60 KJ/min
In 10 min Q = -600 KJ
W = -1.2 KJ/s
We know that
1 min = 60 s
10 min = 600 s
So W = -1.2 x 600 KJ
W = -720 KJ
WE know that ,first law of thermodynamics
Q = W + ΔU
-600 = - 720 + ΔU
ΔU = 120 KJ
The net amount of energy change of the air in the room during a 10-min period is 120 KJ.
