A spherical drop of radius and density is falling in air with terminal velocity. The density of air is and its coefficient of viscosity . The power developed by gravity is

Question

A spherical drop of radius $r$ and density $n$ is falling in air with terminal velocity. The density of air is $n_{0}$ and its coefficient of viscosity $μ$ . The power developed by gravity is

Smart Achievers · Accepted Answer

(3)

$V_{T} = \frac{2}{9} \frac{r^{2} g (ρ_{B} - ρ_{l})}{η}, Power = \vec{F} \cdot \vec{V}$

Solution

Q.
A spherical drop of radius $r$ and density $n$ is falling in air with terminal velocity. The density of air is $n_{0}$ and its coefficient of viscosity $μ$ . The power developed by gravity is

1 $\frac{π r^{5} n}{μ} (n - n_{0}) g^{2}$

2 $\frac{27}{8 μ} r^{5} n (n - n_{0}) g^{2}$

3 $\frac{8 π r^{5}}{27 μ} n (n - n_{0}) g^{2}$

4 $\frac{π r^{5}}{27 μ} n (n - n_{0}) g^{2}$

Ans.
(3)

$V_{T} = \frac{2}{9} \frac{r^{2} g (ρ_{B} - ρ_{l})}{η}, Power = \vec{F} \cdot \vec{V}$

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Solution

Q. A spherical drop of radius r and density n is falling in air with terminal velocity. The density of air is n0 and its coefficient of viscosity μ. The power developed by gravity is

1 πr5nμ(n-n0)g2

2 278μr5n(n-n0)g2

3 8πr527μn(n-n0)g2

4 πr527μn(n-n0)g2

Ans. (3) VT=29r2g(ρB-ρl)η, Power=F→·V→