Weaning Your Baby Onto Solids. The term 'to wean' comes from an ancient phrase that means 'to accustom to'. So weaning refers to the period during which an infant gradually becomes accustomed to food other than milk (breast or formula). Up until 6 months of age, breast or formula milk alone is nutritionally adequate.
Occasional airplane vibration during flight is not unusual. There are many causes of airplane vibration, including landing gear extension and retraction, extension of speed brakes, free play in movable surfaces, and systems malfunctions.
What makes airplanes fly are the four forces of flight, thrust, provided by the engines, propelling the airplane forward, lift pulling the airplane up, drag pulling the airplane back, and weight, or gravity pulling the airplane down. How much an airplane weighs, depends on the plane.