Midterm 3 SECTIONNAM D. Density and Pressure One astronaut is building a baromet
ID: 1788642 • Letter: M
Question
Midterm 3 SECTIONNAM D. Density and Pressure One astronaut is building a barometer using Mercury. In the meantime, clumsy John is playing with a balloon in a mostly Co: (Carbon dioxide) atmosphere on the planet. D-1. Assuming the planet's atmospheric pressure is the same as earth (1 atm = 1.01 × 10s Pa ), find the height of mercury (-13600 kg/m3) on this new planet (g-5.0 m/s). Answer: D-2. Assuming the planet's atmosphere is made of CO2 (p 1.98 kg/m2) on t (o = 1.25 kg/m3) brought from, Earth. planet, find out if the balloon will float. John is filling the balloon using a can of nitrogen (a) What's the buoyant force on a 30.0 em diameter nitrogen balloon? Answer: (b) If the mass of rubber balloon skin is 0.007 g, what's the net upward force on it? (Consider the weight of the balloon = skin + nitrogen) Answer: N Does it float? (Yes or No)Explanation / Answer
D1 ) Atmospheric pressure Po = h rho g
where h is height of mecury
1.01 x 105 = h *13600 *5 ( g on the planet is 5 m/sec2)
h = 1.48 m
D2a) Buoyant force is weght of carbon dioxide displaced = V rho g
V = pi d3 / 6 = 3.5x10-3 m3
rho of co2= 1.98
Buoyant force = 3.5x10-3 *1.98*5 = 3.5x10-2 N
Can't say float or not unless we know weight of balloon skin.
b) Weight of Balloon skin = 0.007x10-3 *5 = 0.0035x10-2 N
weight of Nitrogen in Balloon = 3.5x10-3 *1.25*5 = 2.2x10-2 N
Net force in the upward direction = buoyant force - total weight = 1.29x10-2 N
Hence balloon floats