Author Question: A force of 5.3 N is needed to hold on to an umbrella in a strong wind. If the air molecules each ... (Read 57 times)

formula1 · **on:** Jul 29, 2018

A force of 5.3 N is needed to hold on to an umbrella in a strong wind. If the air molecules each have a mass of 4.7 10-26 kg,

and each one strikes the umbrella (without rebounding) with a speed of 2.0 m/s in the same direction, how many molecules strike the umbrella each second? Assume that the wind blows horizontally so that the gravitational force exerted on the air molecules can be neglected.

Question 2

A spherical ball of lead (density 11.3 g/cm3 ) is placed in a tub of mercury (density 13.6 g/cm3 ). Which answer best describes the result?

A) The lead ball will float with about 17 of its volume above the surface of the mercury.
B) The lead ball will float with about 83 of its volume above the surface of the mercury.
C) The lead will sink to the bottom of the mercury.
D) The lead ball will float with its top exactly even with the surface of the mercury.