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The ancient Greek understanding of physics was limited to the statics of simple machines (the balance of forces), and did not include dynamics or the concept of work. During the Renaissance the dynamics of the Mechanical Powers, as the simple machines were called, began to be studied from the standpoint of how far they could lift a load, in addition to the force they could apply, leading ...
Air flight speed counteracts the jet's exhaust speed. (In an artificial and extreme case with the aircraft flying exactly at the exhaust speed, one can easily imagine why the jet's net thrust should be near zero.) Moreover, since work is force (i.e., thrust) times distance, mechanical power is force times speed. Thus, although the nominal SFC ...
A body remains at rest, or in motion at a constant speed in a straight line, except insofar as it is acted upon by a force. At any instant of time, the net force on a body is equal to the rate at which the body's momentum is changing with time. If two bodies exert forces on each other, these forces have the same magnitude but opposite directions.
Power is the rate with respect to time at which work is done; it is the time derivative of work: =, where P is power, W is work, and t is time. We will now show that the mechanical power generated by a force F on a body moving at the velocity v can be expressed as the product: P = d W d t = F ⋅ v {\displaystyle P={\frac {dW}{dt}}=\mathbf {F ...
In the time interval Δt fluid elements initially at the inflow cross-section A 1 move over a distance s 1 = v 1 Δt, while at the outflow cross-section the fluid moves away from cross-section A 2 over a distance s 2 = v 2 Δt. The displaced fluid volumes at the inflow and outflow are respectively A 1 s 1 and A 2 s 2.
Torque has the dimension of force times distance, symbolically T −2 L 2 M and those fundamental dimensions are the same as that for energy or work. Official SI literature indicates newton-metre, is properly denoted N⋅m, as the unit for torque; although this is dimensionally equivalent to the joule, which is not used for torque.
In classical mechanics, the central-force problem is to determine the motion of a particle in a single central potential field.A central force is a force (possibly negative) that points from the particle directly towards a fixed point in space, the center, and whose magnitude only depends on the distance of the object to the center.
The block-stacking problem is the following puzzle: Place N {\displaystyle N} identical rigid rectangular blocks in a stable stack on a table edge in such a way as to maximize the overhang. Paterson et al. (2007) provide a long list of references on this problem going back to mechanics texts from the middle of the 19th century.