Lifting a weight

On the other hand, if some work is done by the cell (e.g. by turning an electric motor in order to lift a weight) then... 

In the simplest form of a pulley, the grooved wheel is attached to seme immovable object, such as a ceiling or beam. When a person pulls down on one end of the pulley rope, an object at the opposite end of the repe is raised. In a fixed pulley of this design, the mechanical adwitage is cne. That is, a person can lift a weight equal to the force applied. The advantage of the pulley is me of direction. An object can be made to move upward or downward with such a pulley. Venetian blinds are a simple example of the fixed pulley. 

This inability to initiate rotational motion and to lift a weight by preparing a well-tailored wave packet associating all the system eigenstates confirms that such a classical motion is not very natural for quantum systems. The energy AE provided by the initial non-stationary superposition of the rotor states is not fully available to be directed into motion. Without control of the time... 

A boulder perched on the top of a cliff has no kinetic energy because it is not moving. However, it could fall at any moment and then its motion could be harnessed to do work (for example, if attached to a rope and pulley it could lift a weight). Thus, this motionless boulder has the potential to do work that is, it has potential energy. 

Stepwise increases in oil-like character, as when the mildly oil-like Val (V) residue is replaced by the very oil-like Phe (F) residue, cause the add-base titration curves to be shifted to higher pH values and to be steeper. The energy required to drive the model protein from the phase separated, contracted state to the swollen, relaxed state is proportional to the width of the curve, that is, inversely proportional to the steepness of the curve. Accordingly, the model protein with the steepest curve exhibits the most efficient function for performing the work of lifting a weight. 

It has now been possible to stretch a single elastic protein-based polymer chain and to obtain a uniformly increasing force versus extension curve.This was done with a surprisingly simple device called an atomic force microscope, the development of which resulted in the Nobel prize for Paul Hansma. The performance of the mechanical work of lifting a weight, shown in... 

Figure 5.13. A procedure for the formation of elastic model proteins into y-irradiation cross-linked sheets for characterization as elastic-contractile systems for performance of mechemical work of lifting a weight.

Thermal Energy Produces Mechanical Work of Lifting a Weight (Heating Through the Temperature Interval Drives Contraction)... 

Thermal Energy (TE), Measurable as the Heat of the Transition of the Band Under Load, AHi, Produces Mechanical Work (MW) of Lifting a Weight, That Is, TE MW... 

Figure 6.1. Elastic-contractile strip of cross-linked poly(GVGVP) in water contracting to lift a weight (time to half contraction 5 minutes for millimeter thickness, seconds for 50p thick fibers). (Reproduced from Urry. )...

Figure 8.43. Musculature of a man that highlights the biceps muscle, perhaps best recognized for performing the mechanical work of lifting a weight, with a cutaway to an individual muscle fiber, presented as a bundle of myofibrils that contains the fundamental contractile element. (From Fundamentals of Bio-...

When the spine is placed under load as you attempt to lift a weight from the ground, you must develop an extensor moment in the muscles of the spine to permit you to straighten up. Structures which lie close to the center of rotation have a short lever arm and therefore have to generate higher tensile forces to produce the same extensor moment. The tensile forces act to compress the intervertebral disc, and this compressive penalty is highest for the posterior annulus and is lowest for the lumbodorsal fascia. 

An isotonic type of contraction (reduction in length under constant stress) is exemplified by an isolated muscle excited to lift a weight hanging on one end - see Fig. 9.8. (The cross-sectional area experiencing loading is assumed to remain approximately constant.) By fixing both ends and applying an... 

It will be recognized that statements similar to this are met with in other branches of physics. Thus the work required to lift a weight between two points in a gravitational field, or to move a charge between two points in an electric field, is the same whatever is the path. In both of these examples it is possible to define a potential function, such that the work done on a body in taking it from an initial state to a final state B is equal to b — < a where and depend only on the states A and B— i.e. they are independent of the path. 

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