Question

1. an irregularly - shaped object displaces 32 ml of water. it has a density of 28 g/ml. determine the mass of the object.
2. a rock dropped in a graduated cylinder raises the level of water from 20 ml to 35 ml. the rock has a mass of 45 g. what is the density of the rock?

Explanation:

Step1: Recall density formula

The density formula is $
ho=\frac{m}{V}$, where $
ho$ is density, $m$ is mass and $V$ is volume. For the first problem, we can re - arrange it to $m =
ho V$. For the second problem, we use $
ho=\frac{m}{V}$ directly.

Step2: Solve problem 23

Given $
ho = 28\ g/mL$ and $V=32\ mL$. Substitute into $m=
ho V$.
$m = 28\ g/mL\times32\ mL=896\ g$

Step3: Solve problem 24

First, find the volume of the rock. The volume of the rock is equal to the volume of water it displaces. $V=35\ mL - 20\ mL = 15\ mL$. Given $m = 45\ g$. Substitute into $
ho=\frac{m}{V}$.
$
ho=\frac{45\ g}{15\ mL}=3\ g/mL$

Answer:

1. 896 g
2. 3 g/mL