The energetic cost of moving about

Kinetic energy is the ability of an object in motion to do work or enact change. It can take on many forms. For instance, water flowing down a waterfall has kinetic energy. In biological systems, particles of light travel and are absorbed by plants to create chemical energy. Animals consume the chemical energy and give off molecules that carry their scent through the air. They also generate kinetic energy when they run away from predators. Entire systems also possess kinetic energy, like the...

It’s plausible to suppose that the greater the velocity of a body, the greater effect it could have on other bodies. This does not depend on the direction of the velocity, only its magnitude. At the end of the seventeenth century, a quantity was introduced into mechanics to explain collisions between two perfectly elastic bodies, in which one body makes a head-on collision with an identical body at rest. When they collide, the first body stops, and the second body moves off with the initial...

The kinetic energy of a particle is one-half of the product of the particle’s mass and the square of its speed. Note that just as Newton’s second law can be expressed as either the rate of change of momentum or mass multiplied by the rate of change of velocity, so too can the kinetic energy of a particle be expressed in terms of its mass and momentum, instead of its mass and velocity.

The dynamics of a mechanical system can be easily understood by interpreting a potential energy diagram. Since energy is a scalar quantity, the interpretation of the dynamics of the system becomes even simpler.
Take the example of a skater on a parabolic ramp. The potential energy at different points along the ramp will be proportional to the height of the ramp, which varies quadratically with the horizontal position on the ramp. As the skater moves down the ramp from the highest position,...

Imagine a solid object involved in a general planar movement, with its center of mass pinpointed at a spot labeled G. The object's kinetic energy relative to an arbitrary point A can be quantified for each of its particles - the ith particle in this case. This measurement is achieved through the employment of the relative velocity definition. The position vector, known as rA, extends from point A to the mass element i.

Active transport is a critical biological process that allows cells to move solutes against an electrochemical gradient. This process requires direct energy input and is characterized by its selectivity, saturability, and susceptibility to competitive inhibition.
Primary active transporters, like Na+, K+ and -ATPase, directly utilize ATP to move ions across the membrane. These transporters play significant roles in various physiological processes. For instance, Na+, K+ and -ATPase maintain...