Chapter SH, Problem 24.9APP

To determine

To calculate: Decrease in the mass of car made by using plastic instead of steel.

Answer to Problem 24.9APP

Decrease in the mass of car made by using plastic instead of steel is $\underset{\_}{200\text{ kg}}$ .

Explanation of Solution

Given:

Amount of plastic parts in the car = $200\text{ kg}$

Density of steel is twice the density of plastic.

Volume of the plastic parts equals the volume of the same parts made of steel.

Formula used:

Density is given by,

  $D=\frac{m}{V}$

Where m is mass and V is volume.

Calculation:

Since density of steel is twice the density of plastic and olume of the plastic parts equals the volume of the same parts made of steel,

  $\begin{array}{l}{D}_{\text{steel}}=2D_{\text{plastic}}\\ \frac{m_{\text{steel}}}{v}=2\frac{m_{\text{plastic}}}{v}\\ m_{\text{steel}}=\frac{2\times 200\text{ kg}\times v}{v}\\ m_{\text{steel}}=400\text{ kg}\end{array}$

Decrease in the mass of car in using plastic in place of steel is calculated as:

  $400-200=200\text{ kg}$

Conclusion:

Decrease in the mass of car made by using plastic instead of steel is $\underset{\_}{200\text{ kg}}$ .