Thursday, 4 January 2018

BIO MECHANICS - UNIT-1 PART-A

By Ask Biomedical
                        askbiomedical
  
                              UNIT 1
                           
                           PART A

1.Define stress. (N/D2014)

Stress is way of responding to any kind of demand or threat in a body or the deformation caused in a body by a force. This reaction is known as "fight-or-flight,” or the stress response. During stress response, your heart rate increases, breathing quickens, muscles tighten, and blood pressure rises.    

2.Define Pseudo Elasticity. (N/D2014)

Pseudoelasticity, sometimes called superelasticity, is an elastic (reversible) response to an applied stress, caused by a phase transformation between the austenitic martensitic phases of a crystal. It is exhibited in shape -memory alloys.

3.What is Non-Newtonian Fluid?(N/D2014)
 A non-Newtonian fluid is a fluidthat does not follow Newton's Law of Viscosity. Most commonly, the viscosity (the measure of a fluid's ability to resist gradual deformation by shear or tensile stresses) ofnon-Newtonian fluids is dependent on shear rate or shear rate .

4.Sate Hooke’s law.(N/D2010)
Hooke's law is a principle of physics that states that the force (F) needed to extend or compress a spring by some distance X scales linearly with respect to that distance.
            F = kX,
where k is a constant factor characteristic of the spring: its stiffness, and X is small compared to the total possible deformation of the spring.

5.Define viscoelasticity. (M/J2013)

Viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like honey, resist shear flow and strain linearly with time when a stress is applied.

6.Difference between Newtonian and non Newtonian fluid (M/J2011)

A Newtonian fluid's viscosity remains constant, no matter the amount of shear applied for a constant temperature.. These fluids have a linear relationship between viscosity and shear stress.

 Non-Newtonian fluids are the opposite of Newtonian fluids. When shear is applied to non-Newtonian fluids, the viscosity of the fluid changes.

Draw the stress Vs strain curve representing the materials Properties?



7.Define kinetic and dynamic viscosity?

To measure a fluid’s resistance to flow when an external force is applied. It  is called  Dynamic Viscosity. kinematic viscosity is the measure of a fluid’s inherent resistance to flow when no external force, except gravity, is acting on it.

8.Differentiate kinetics and kinematics

Kinetics is a term for the branch of classical mechanics that is concerned with the relationship between the motion of bodies and its causes, namely forces and torques. 

 Kinematics is the branch of classical mechanics which describes the motion of points, bodies (objects) and systems of bodies (groups of objects) without consideration of the causes of motion.

In Kinetics, velocities, accelerations and the forces which creates the motion.

In Kinematics,  velocities and accelerations without the forces/torques which creates the motion. 

9.Define Newton's law of viscosity.(M/J2011)

Newton's viscosity law's states that, the shear stress between adjacent fluid layers is proportional to the velocity gradients between the two layers. The ratio of shear stress to shear rate is a constant, for a given temperature and pressure, and is defined as the viscosity or coefficient of viscosity.

10.Define Hooke’s law of elasticity (M/J 2013)

Hooke's law, law of elasticity discovered by the English scientist Robert Hooke in 1660, which states that, for relatively small deformations of an object, the displacement or size of the deformation is directly proportional to the deforming force or load.
                    F = kX,



                            

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