Question

The object on the right is made from a square-based pyramid joined to a cuboid.

Answer 1

Answer:

Density of steel = 80.73 gm/$cm^3$

Step-by-step explanation:

The figure is made up of cuboid and square pyramid.

Height of cuboid, h = 9 cm

Length of cuboid, l = 6 cm

Width of cuboid, w = 6 cm

Volume of cuboid is given by the formula:

$V_{Cuboid} = l \times w \times h$

$V_{Cuboid} = 6 \times 6 \times 9\\\Rightarrow V_{Cuboid} = 324\ cm^3$

Density of Wood , $D_{Cuboid}$= 0.68g/$cm^3$

We know that formula of Density is:

$Density = \dfrac{Weight}{Volume}$

$D_{Cuboid} = \dfrac{W_{Cuboid}}{V_{Cuboid}}\\\Rightarrow W_{Cuboid} = V_{Cuboid} \times D_{Cuboid}$

Putting the values:

$W_{Cuboid} = 324 \times 0.68 = 220.32\ gm$

Total weight = $W_{Cuboid} + W_{Pyramid}$

970 = 220.32 $+ W_{Pyramid}$

$W_{Pyramid}$ = 749.68 gm

Volume of pyramid is given as:

$V_{Pyramid}= \dfrac{1}{3} \times \text{Area of Base} \times \text{Vertical Height}$

Base is a square with side 6 cm

$V_{Pyramid}= \dfrac{1}{3} \times 6 \times 6 \times (17 -9)\\V_{Pyramid}= 96\ cm^3$

Density of Steel/Pyramid:

$D_{Pyramid} = \dfrac{W_{Pyramid}}{V_{Pyramid}}\\\Rightarrow D_{Pyramid} = \dfrac{749.68}{96}\\\Rightarrow D_{Pyramid} = 80.73\ gm/cm^3$