(i) Express $5\ cm$ in metre and kilometre.
(ii) Express $35\ mm$ in $cm, m$ and $km$.

AcademicMathematicsNCERTClass 7

To do :

(i) We have to express $5\ cm$ in meter and kilometer.

(ii) We have to express $35\ mm$ in $cm, m$ and $km$.

Solution :

(i) We know that,

$1\ km = 1000\ m$ and $1\ m = 100\ cm$

This implies,

$1\ cm = \frac{1}{100}\ m = 0.01\ m$

$1\ cm = 0.01 \times 1\ m$

$= 0.01 \times \frac{1}{1000} km$

$= 0.01 \times 0.001\ km$

$= 0.00001\ km$

Therefore,

$5\ cm = 5 \times 0.01\ m$

$= 0.05\ m$

$= 5 \times 10^{-2}\ m$.

$5\ cm = 5 \times 0.00001\ km$

$= 0.00005\ km$

$= 5 \times 10^{-5}\ km$.

(ii) We know that,

$10\ mm=1\ cm$

This implies,

$1\ mm=\frac{1}{10}\ cm$

$35\ mm=35\times\frac{1}{10}\ cm$

$35\ mm=3.5\ cm$

Now, converting $3.5\ cm$ to $m$, we get,

$100\ cm=1\ m$

This implies,

$1\ cm=\frac{1}{100}\ m$

Therefore,

$3.5\ cm=3.5\times\frac{1}{100}$

$3.5\ cm=0.035\ m$

Again, converting $0.035\ m$ into $km$

$1000\ m=1\ km$

This implies,

$1\ m=\frac{1}{1000}\ km$

Therefore,

$0.035\ m=0.035\times\frac{1}{1000}\ km$

$0.035\ m=0.000035\ km$

raja
Updated on 10-Oct-2022 13:32:37

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