List five precautions to be taken when using cranes and hoists in underground constructions
What will be an ideal response?
• All tools or materials to be raised or lowered must be stacked or secured to prevent shifting or snagging.
• When a load is being moved, flashing warning lights should be used to make sure that employees are aware that a load is being lowered or raised.
• To guard against malfunctioning of operational controls, limit switches and anti-two-block devises must be used to limit the undesired travel of loads.
• When maintenance and repair work is to be undertaken in a shaft served by a cage, bucket, or skip, employees must be alerted before the work commences.
• When work is being performed in a given shaft, warning signs must be placed in clearly visible locations at each underground landing, at he shaft collar, and at he operator's station.
• Connectors must be used between the hoisting rope and cage skip that are compatible with the wire rope being used to lift the hoist.
• Cage, skip, and load connectors must be used that can withstand the force of the hoist pull, vibration, misalignment, or impact without disengaging.
• All spin connectors must be kept in a properly maintained, clean working condition.
• Proper searing of wire rope wedge sockets must be ensured when they are used.
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Verify that the flow is turbulent.
The mechanical-energy balance provides a basis for estimating pressure drop owing to friction in fluid flow. For steady flow of an incompressible fluid in a horizontal pipe of constant cross-sectional area, it may be written,
where 
is the Fanning friction factor. Churchill gives the following expression for 
for turbulent flow:
Here, Re is the Reynolds number and ? /D is the dimensionless pipe roughness. For pipe flow, Re ? u?D/?, where D is pipe diameter and ? is dynamic viscosity. The flow is turbulent for Re > 3000.
Consider the flow of liquid water at 25°C. For one of the sets of conditions given below, determine 
and 
Assume ? /D = 0.0001. For liquid water at 25°C, ? = 
, and ? =
(a) D = 2 cm, u = 1
(b) D = 5 cm, u = 1
(c) D = 2 cm, u = 5 
(d) D = 5 cm, u = 5
The main characteristic of static electricity is that a prolonged or steady flow of current is not possible.
Answer the following statement true (T) or false (F)
The coefficient of friction is found by ________
A) Multiplying the tensile force by the weight force B) Multiplying the weight force by the tensile force C) Dividing tensile force by weight force D) Dividing weight force by tensile force
Technician A says sensible heat can be measured. Technician B says specific heat is the amount of heat required to change one pound of a substance by 1°F. Who is correct?
A. Technician A only B. Technician B only C. Both A and B D. Neither A nor B