Vibration of vibration are pulling a child back on a swing and letting it go, or hitting a tuning fork and letting it ring. The mechanical system vibrates at one or more of its natural frequencies and damps down to motionlessness. Forced vibration is when a time-varying disturbance (load, displacement or velocity) is applied to a mechanical system. The disturbance can be a periodic and steady-state input, a transient input, or a random input. The periodic input can be a harmonic or a non-harmonic disturbance. Examples of these types of vibration include a washing machine shaking due to an imbalance, transportation
Edible protein per unit area of land usable protein per unit area than any other major vegetable or grain crop, except for hemp which can produce up to . They produce 5 to 10 times more protein per unit area than land set aside for grazing animals to make milk, and up to 15 times more protein per unit area than land set aside for meat production. Selected averages as computed in the 1970s. Edible protein per unit area of land Edible protein per unit area of land is a measure of agricultural productivity. This measure for various major foodstuffs is shown in the chart below. Values