50 Questions
What is the purpose of dynamic force analysis?
Evaluating input forces or torques
How is the inertia force defined?
Opposite in magnitude and direction to the accelerating force
What is the relationship between inertia torque and accelerating couple?
Opposite in magnitude but equal in direction
How can a system of forces acting on a rigid body be reduced?
To a single resultant force and a couple
What creates a couple on a rigid body?
Two equal and opposite forces acting through the center of gravity
What is the inertia torque?
- Imaginary torque bringing a rigid body to equilibrium
What term describes the distance a screw thread advances axially in one turn?
Lead
Which type of thread is stronger and offers more resistance to motion than square threads?
V-threads
What is the principle on which a screw jack works similar to?
Inclined plane
What is the curve traced by a particle moving along a screw thread at a uniform speed?
Helix
Which type of screw threads are generally used for tightening pieces like bolts and nuts together?
V-threads
What term refers to the difference between the top and bottom surfaces of a screw thread?
Depth of thread
What does D-Alembert's principle state about the resultant force and inertia force?
They are in equilibrium.
What is the equivalent static problem obtained from reducing a dynamic problem using D-Alembert's principle?
Reduced to a single resultant force acting on the body.
Which type of screw threads are used in screw jacks and vice screws?
Square threads
What does the equation F + FI = 0 represent in D-Alembert's principle?
Resultant force equals reversed effective force.
What is the main function of a screw jack?
To lift or lower a load
In the context of a screw jack, what does the coefficient of friction µ represent?
The friction between the screw and nut
What is the relationship between the effort applied (P) and the load (W) in a screw jack?
$P = W \times \tan(a+f)$
When using a V-thread, how does the normal reaction between the screw and nut differ compared to a square threaded screw?
It is equal to the axial load W
In a journal bearing, what happens when there is no lubrication present?
A greasy friction occurs with line contact
What is the purpose of a thrust collar in relation to a screw jack?
To prevent the load from rotating with the screw
How does the total torque required to rotate a screw change when an effort P1 is applied at the end of a lever?
$P1$ increases the torque required
What force does a screw jack leverage to lift or lower a load?
$F = P \times \cos(a)$
How does friction change between a screw and nut when using a V-thread instead of a square threaded screw?
$f$ increases due to increased surface area
What is the role of the frictional force F in relation to the shaft rotation?
Acts at the circumference of the shaft to rotate it in the opposite direction
What must be true for the resultant force acting on the shaft for uniform motion?
It must be zero
In terms of resultant turning moment on the shaft, what condition is necessary for uniform motion?
It must be zero
What is the relationship between T (frictional torque) and ø according to the provided text?
$T = W \times r \tan{\theta}$
What is used to take the axial thrust of rotating shafts like those in ships and turbines?
Ball and roller thrust bearings
What condition is assumed in the study of bearing friction as per the text?
The pressure is uniformly distributed throughout the bearing surface
When a vertical shaft rotates in a flat pivot bearing, where does the sliding friction occur?
Along the surface of contact between the shaft and bearing
'Truncated or trapezoidal pivot' terminology refers to what kind of pivot?
"Pivot with a truncated cone as bearing"
'Foot step bearing' terminology commonly refers to which type of pivot bearing?
"Flat pivot bearing"
What is considered when there is uniform pressure in a flat pivot bearing?
Wear rate depends on velocity and intensity of pressure.
What is another name for collar bearings?
Thrust bearings
In the context of collar bearings, what does the symbol r1 represent?
External radius of the collar
What does the coefficient of friction of 0.12 refer to in the context of collar bearings?
Intensity of pressure
When considering uniform wear in collar bearings, what does the total load transmitted to the collar represent?
Total frictional torque on the collar
What does the symbol d1 = 600 mm or r1 = 300 mm represent in Example 1?
External diameter of the collars
What does the intensity of pressure of 0.35 N/mm2 refer to in Example 2?
Load carried by the shaft
What is the assumption made about the rate of wear in bearings?
It is proportional to the product of intensity of pressure and velocity.
What is the formula for power lost in friction given the coefficient of friction and load?
$P = \mu \times W \times N$
In the context of bearings, what does 'dl' represent?
The length of the ring along the cone.
What does 'C/r' represent in the context of uniform wear in bearings?
A measure of intensity of pressure
What is the formula for total torque acting on a conical pivot bearing?
$T = \int_{r1}^{r2} pn\cdot A,dr$
In a frustum bearing, what does '2pC.dr' represent?
The load transmitted to the ring.
What does '301.76' represent in calculating the power absorbed in friction?
$\mu$ (coefficient of friction)
How is 'dl' related to 'dr' in bearing calculations?
'dl' is a function of 'dr'.
What information does 'pn × 2pr.drcosec a' provide?
Normal load acting on the ring.
Test your knowledge on static and dynamic force analysis, including evaluation of input forces, torques, joint forces, and inertia force. Learn about the concept of inertia force and its application in bringing a rigid body into equilibrium position.
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