Mech Viva Ans

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Mechanics VIVA QUESTIONS
Q.Look around in the lab and tell me how many Trusses do you see
around.
A.Say the aluminium window panes
Q.Where is a flywhele most commonly used? And what is its primary
use?
A.Its primarily used in a printing press, and its used
mainly to store large amount of energy,in short bursts of time.
Q.In the room,which one is the beam and which one is the
column?
A beam supports horizontally
A column supports vertically n building structures, columns are connected to different footings to transfer the load of
the building to the footings of the building. Beams in a structure is used to carry the loads from the slabs to the
columns.
Q.Can a frictionless surface exist in reality?
No
Q.What is reaction,or define reaction?

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The third of Newton's laws of motion of classical mechanics states that forces always occur in pairs. Every action is
accompanied by a reaction of equal magnitude but opposite direction. A reaction force is bascally a force that acts in
the opposite direction to an action force.
Q.What is equilibrium?Explain it with rough diagram? Q.Conditions
for Equilibrium?
Fx=0 Fy=0 moment about any point=0
Q.What is pressure?
Pressure is the force per unit area applied in a direction perpendicular to the surface of an surface.
Q.What is the difference between Couple and Moment?
The moment of a force is the perdendicular force F acting at a distance, d and causes an object to rotate.
If two opposite moments act to cause an object to rotate, such as when your two hand on a car steering wheel, it is
called a couple.

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Q.Given the force in a diagram, find the moment?
Depends on question asked.
Q.Can coplanar forces be applied to any force system.?
Q.Define coefficient of Restitution.
The coefficient of restitution of two colliding objects is a fractional value representing the ratio of speeds
after and before an impact, taken along the line of the impact
Q.Angle of Repose.
The angle of repose is the steepest angle of the slope relative to the horizontal plane when material on the
slope face is on the verge of sliding
Q.Angle of Friction.
Angle of Friction is one for which the items will begin sliding. This is called the angle of friction or friction angle. It
is defined as:

Q.What is force scale?
The Force Scale measures kinetic or concusive pressures created by things.
Q.Why is mu(s) greater than mu(k).

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Think of surfaces not as smooth, but as rough with many hills and valleys. When the objects are not moving (relative
to each other), these hills and valleys can line up and maximize the force between them. When the objects are
moving, the hills and valleys don't get a chance to line up, thus it takes less force to keep the object moving than it
does to make it start moving.
Q.Law of Friction.
1. The force of friction is directly proportional to the applied load.
2. The force of friction is independent of the apparent area of contact.
3. Kinetic friction is independent of the sliding velocity.

Q.Range of mu(s).
0.2 to 0.6
Q.Formula of belt friction,What is theta in this?

T1=T2e
is the angle, in radians formed by the first and last spots the belt
touches the pulley, with the vertex at the center of the pulley.
Q.Can acceleration due to gravity be more than 10 m/s2.If yes
then where?
No not on earth.Gravity is maximum on surface of earth. It decreases as we move up the surface or deeper in
surface. Also gravity is maximum on surface at the poles which in 9.81 m/s2.However gravity can be greater than
10m/s2 on some other planet which is more denser than earth.
Q.If six forces are there out of which 4 are given and 2 are
unknown and angles of all the forces are given,can we
construct the hexagon on graph and find the two unknown
forces?(Graphical explanation expected).

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Yes.
Q.Reason for difference in analytical and experimental
values.
Human error Frictional force Air resistance Assumption like inextensible or weightless string
Q.Explain Co-planar forces.
Refer notes or any standard text books.
Q.State various Types of Supports.
Refer notes or any standard text books.
Q.Define angle of Respose.
Refer notes or any standard text books.
Q.Define angle of Friction.
Refer notes or any standard text books.

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Q.If the angle of repose between these two lines,the object
is just moving then will the angle between these two lines will also
be angle of repose?
Q.What is restitution?
Refer notes or any standard text books.
Q.What is plastic collision?
Refer notes or any standard text books.
Q.What is elastic collision?
An elastic collision is an encounter between two bodies in which the total kinetic
energy of the two bodies after the encounter is equal to their total kinetic energy
before the encounter. Elastic collisions occur only if there is no net conversion
of kinetic energy into other forms.
Q.What is limiting friction?
LIMITING FRICTION is defined as the maximum force of friction that can be generated between two static
surfaces.When the magnitude of force applied to a body exceeds the limiting friction the body comes into the state
of motion.

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Q.What is the coefficient of restitution of plastic
collision?
a perfectly-inelastic or plastic collision has a coefficient of restitution of zero.
Q.What is the coefficient of restitution equal to 1?
A perfectly elastic collision has a coefficient of restitution of 1
Q.Tod draw fbd of diagram the force system type and type of
support(Simple Support).
Depends on question asked.



Best Of Luck to ALL from ~~Rahul

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