Li cas los xam cov naj npawb ntawm cov meters

Piv txwv li, cov qauv ntaub tsis-woven muaj lub hauv paus hnyav ntawm 50g / m2 thiab qhov dav ntawm 1m. Qhov hnyav ntawm qhov tsis-yog ntaub yog 1g ib 'meter': 50g / m2 * 1m * 1m = 50g, tom qab ntawd koj xav tau ib kilo (1000g). Rau cov ntaub ntawv, nws xav tau: 50g / m2 * 1m * 20m = 1000g, uas yog hais, cov ntaub npuag tsis muaj qhov dav nrog qhov dav ntawm 1m thiab qhov hnyav 50g / m2 yog 20m ntev thiab tsis hnyav 1kg.