1. A 4 kg block of some unknown material is suspended from a spring scale and su
ID: 1552654 • Letter: 1
Question
1. A 4 kg block of some unknown material is suspended from a spring scale and submerged in water. The spring scale reads 33.7 N.
a) What's the specific gravity of the block?
b) What's the density of the block?
2. A recreational hot air spherical balloon has a radius of 6.9 m when fully inflated. The total weight of the balloon, basket, ballast and pilot is 2130 N. When the balloon's released from its mooring, it moves upward and reached a terminal velocity of VT = 0.75 m/s. If the air resistance is given by F = bvT, where b = 2610 kg/s. What's the density of the hot air in the balloon? The density of the surrounding air is 1.293 kg/m3.
Explanation / Answer
1)
F = mg
F = 4 x 9.81 = 39.24 N
With water, it reads, 33.7 N
So, the buoyant force = 39.24 - 33.7 = 5.54 N
Buoyancy = Vg = (1000)V(9.81) = 5.54
V = 5.65 x 10^-4 m^3
Mass of the object = 4 kg
Density = 4 / (5.65 x 10^-4) = 0.70796 x 10^4 = 7079.6 kg / m^3 .............Ans(b)
Specific gravity = density / density of water = 7079.6 / 1000 = 7.0796 ........Ans(a)
2)
The difference between the weight of the internal and external air, then, is 2130 N.
volume V = (4/3)r^3 = 1375 m^3
(_air - )*g*V = 2130 N
(1.293 - ) * 9.81 * 1375 = 2130
1.293 - = 0.1579
= 1.1351 kg/m^3
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.