Water is pumped from a lower reservoir to a higher reservoir by a pump that provides 20 kW of shaft power. The free surface of t
he upper reservoir is 45 m higher than that of the lower reservoir. If the flow rate of water is measured to be 0.03 m3 /s, determine mechanical power that is converted to thermal energy during this process due to frictional effects.
1 answer:
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Answer:
0.024 m = 24.07 mm
Explanation:
1) Notation
= tensile stress = 200 Mpa
= plane strain fracture toughness= 55 Mpa
= length of a surface crack (Variable of interest)
2) Definition and Formulas
The Tensile strength is the ability of a material to withstand a pulling force. It is customarily measured in units (F/A), like the pressure. Is an important concept in engineering, especially in the fields of materials and structural engineering.
By definition we have the following formula for the tensile stress:
(1)
We are interested on the minimum length of a surface that will lead to a fracture, so we need to solve for
Multiplying both sides of equation (1) by
(2)
Sequaring both sides of equation (2):
(3)
Dividing both sides by we got:
(4)
Replacing the values into equation (4) we got:
3) Final solution
So the minimum length of a surface crack that will lead to fracture, would be 24.07 mm or more.
Answer:
μ = 0.136
Explanation:
given,
velocity of the car = 20 m/s
radius of the track = 300 m
mass of the car = 2000 kg
centrifugal force
F c = 2666. 67 N
F f= μ N
F f = μ m g
2666.67 = μ × 2000 × 9.8
μ = 0.136
so, the minimum coefficient of friction between road surface and car tyre is equal to μ = 0.136