Question

The surface tension of water is 72 dyne\cm. Convert it in SI unit

Answer 1

72 dyne / cm
   = 72 * gm - cm/sec^2 / cm
   = 72 * 10^-3 kg- 10^-2 m/sec^2 /10^-2 m
   = 0.072 kg-m/sec^2 /m
    = 0.072 N/m

Answer 2

Answer:

In SI unit the surface tension of water is 0.072 N/m .

Explanation:

Dyne and Newton, both are units of force. While Dyne is specified in C-G-S(Centimeter – Gram – Second) unit system, Newton is specified in modern SI unit system.

We know that 1 Newton = $\bold{10^{5}}$  dyne.  

Explanation of how 1 Newton = $10^{5}$ is as below,

So converting $\left[\mathrm{Kg} \times \mathrm{m} / \mathrm{S}^{2}\right] \rightarrow\left[\mathrm{g} \times \mathrm{cm} / \mathrm{S}^{2}\right]$

$=(1000 \mathrm{gm}) \times(100 \mathrm{cm}) / 1 \text { Second }^{2}=10^{5} \mathrm{gm} \times \mathrm{cm} / \mathrm{S}^{2}=10^{5}$

Here surface tension of water is 72 dyne\cm.

1 Newton = $72 \times \frac{10^{-5}}{10^{-2}}$ Newton/Meter

Hence surface tension of water will be $72 \times 10^{-3} \mathrm{N} / \mathrm{m}$ i.e. 0.072 N/m