PT 505 Lecture Notes - Lecture 2: Ground Reaction Force, Free Body Diagram, Angular Acceleration

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bluecockroach554

9 Nov 2020

School

Quinnipiac University

Department

Physical Therapy

Course

PT 505

Professor

David Wallace

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Document Summary

Ch 4: biomechanical principles see also print out- concepts from biomechanics: newton"s laws: underlying principles of biomechanics, newton"s first law: law of inertia. A body remains at rest or at a constant linear velocity except when compelled by an external force to change its state. A body remains at rest or at a constant angular velocity around an axis of rotation unless compelled by an external torque to change its state. The linear acceleration of a body is directly proportional to the force causing it, takes place in the same direction in which the force acts, and is inversely proportional to the mass of the body. F = m * a units = n. The angular acceleration of a body is directly proportional to the torque causing it, takes place in the same rotatory direction in which the torque acts, and is inversely proportional to the mass moment of inertia of the body. T = i * units = nm.

Related Questions

1. If an object is rotating clockwise, this corresponds to a _____ angular velocity:

a- negative

b- positive

2. The angular displacement of a rotating object is measured in

a- degrees per second

b- degrees

c- radians

3. Which factor does the torque on an object NOT depend on?

a- the angle at which the force is applied

b- the object's angular velocity
c- the magnitude of the applied force

4. A net torque applied to an object causes __________.

a- the object to rotate at a constant rate
b- a linear acceleration of the object
c- the moment of inertia of the object to change
d- the angular velocity of the object to change

5. For an extended object, the weight force can be considered to act at which point?

a- At the center of gravity of the object
b- At the center of the object
c- At end of the object closest to the ground
d- At the end of the object farthest away from the ground

6. Moment of inertia is __________.

a- the rotational equivalent of mass
b- the point at which all forces appear to act
c- the time at which inertia occurs

peachgrasshopper627

A wheel free to rotate about its axis that is not frictionless isinitially at rest. A constant external torque of +57 NÂ·m is appliedto the wheel for 24 s, giving the wheel an angular velocity of +660rev/min. The external torque is then removed, and the wheel comesto rest 120 s later. (Include the sign in your answers.)
(a) Find the moment of inertia of the wheel.

kgÂ·m2

(b) Find the frictional torque, which is assumed to beconstant.

NÂ·m

A wheel free to rotate about its axis that is not frictionless isinitially at rest. A constant external torque of +48 NÂ·m is appliedto the wheel for 24 s, giving the wheel an angular velocity of +590rev/min. The external torque is then removed, and the wheel comesto rest 120 s later. (Include the sign in your answers.)
(a) Find the moment of inertia of the wheel. (kg*m^2)

(b) Find the frictional torque, which is assumed to be constant.(N*M)

PT 505 Lecture Notes - Lecture 2: Ground Reaction Force, Free Body Diagram, Angular Acceleration

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Physics: Principles with Applications

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