Balloons are sometimes filled with helium gas because it has a mass only about one-seventh that of air under identical conditions. the buoyancy force, which may be expressed as fb = g vballoon, will push the balloon upward. if the balloon has a diameter of 10 m and carries two people having a mass of 70 kg each and the mass of the gondola is 64 kg, determine the acceleration of the balloon when it is first released. assume that the density of the air is = 1.16 kg/m3 , and neglect the weight of the ropes and balloon envelope fab

Select the correct answer. anna will wear a black dress when she attends het cousin's wedding. which color(s) does the dress absorb? a. all colors b. no colors c. red and green d. white

Unpolarized light falls on two polarizer sheets whose transmission axes are at right angles. a third polarizer is placed between the first two so that its axis makes a 52-degree angle with the axis of the first polarizer. a) what fraction of the incident light intensity is transmitted through the first polaroid? b) what fraction of the incident light intensity is transmitted through the second polaroid? c) what is the angle of polarization of the light that enters the third polaroid? d) what fraction of the incident light intensity is transmitted through the third polaroid. e) what happens if the middle polaroid is removed?

What happens when a rubber rod is rubbed with a piece of fur?