91Ó°ÊÓ

The given data can be listed below,

• The mass of the box is, m=36 kg .
• The new mass of the box is, ${\mathrm{m}}_{\mathrm{N}}=71\mathrm{kg}$.

Any movement in the air encounters air resistance. The collision of a moving item with air molecules causes this effect.

When box is falling at terminal velocity, acceleration on the falling box is zero. net force is given by,

${\mathrm{F}}_{\mathrm{net}}=0$

The air resistance force is equal to the gravitational force which is given by,

role="math" localid="1657800089151" $F_r=F_g$

So, the air resistance of the box is given by,

$F_r=mg$

Here, m is the total mass of the box and g is the acceleration due to gravity.

Substitute all the values in the above,

$$\begin{gathered} {\mathrm{F}}_{\mathrm{r}}=\left(36\mathrm{kg}\right)\left(9.8\mathrm{m}/{\mathrm{s}}^2\right)\left(\frac{1\mathrm{N}}{1\mathrm{kg}.\mathrm{m}/{\mathrm{s}}^2}\right) \\ =352.8\mathrm{N} \end{gathered}$$

Thus, the magnitude of the air resistance of the box is =352.8 N.

The magnitude of the air resistance force is given by,

$F_{net}=0$

Here, m is the new mass of the box and gis the acceleration due to gravity.

$F_r=F_g$

Substitute all the values in the above,

$F_r=mg$

$$\begin{gathered} {\mathrm{F}}_{\mathrm{r}}=\left(71\mathrm{kg}\right)\left(9.8\mathrm{m}/{\mathrm{s}}^2\right)\left(\frac{1\mathrm{N}}{1\mathrm{kg}.\mathrm{m}/{\mathrm{s}}^2}\right) \\ =696\mathrm{N} \end{gathered}$$

Thus, the magnitude of the magnitude of the air resistance force acting upward on the falling box of mass 71 kg is 696 N .