If the value of surface tension of a liquid is 70 dynes / cm, then its value in N / m will be :

Question

If the value of surface tension of a liquid is 70 dynes / cm, then its value in N / m will be : (A) 7 × 103 N / m (B) 7 × 102 N / m (C) 7 × 10-2 N / m (D) 70 N / m

Tardigrade Admin · Accepted Answer

The unit dynes/cm is CGS system of unit. The CGS unit of force is dyne and SI unit is Newton. Also there are 105 dynes in one newton and 100 cm in 1 m. ∴ (70 text dynes / cm )=(70 × 10-5/10-2) =7 × 10-2 N / m

Q. If the value of surface tension of a liquid is $70$ dynes / cm, then its value in $N / m$ will be :

$7 \times 1 0^{3} N / m$

$7 \times 1 0^{2} N / m$

$7 \times 1 0^{- 2} N / m$

$70 N / m$

The unit dynes/cm is $CGS$ system of unit.
The CGS unit of force is dyne and $S I$ unit is Newton.
Also there are $1 0^{5}$ dynes in one newton and $100 c m$ in $1 m$ .
$∴ \frac{70 dynes}{c m} = \frac{70 \times 1 0 ^{- 5}}{1 0 ^{- 2}}$
$= 7 \times 1 0^{- 2} N / m$

Q. If the value of surface tension of a liquid is 70 dynes / cm, then its value in N/m will be :

7×103N/m

7×102N/m

7×10−2N/m

70N/m