+0  
 
0
327
1
avatar

A block of steel (d=8.05g/cm3) weighs 157.4kg. How many whole solid cylindrical pegs with a radius of 0.500in. and a length of 2.00 in. can be made?

Guest Jul 11, 2014

Best Answer 

 #1
avatar+26626 
+5

Volume of one cylindrical peg = pi*r2*L  where r is the radius and L is the length.

Here we have r = 0.5 inches = 0.5*2.54 cm = 1.27 cm,  and L = 2 inches = 2*2.54 cm = 5.08 cm

The volume of one peg = pi*1.272*5.08 cm3.

The mass of one peg is given by volume*density = pi*1.272*5.08 cm3 * 8.05 g/cm3 = pi*1.272*5.08*8.05 g

So the number of these you can get out of a block of mass 157.4kg is 154.7*1000/(pi*1.272*5.08*8.05)

$${\frac{{\mathtt{157\,400}}}{\left({\mathtt{\pi}}{\mathtt{\,\times\,}}{{\mathtt{1.27}}}^{{\mathtt{2}}}{\mathtt{\,\times\,}}{\mathtt{5.08}}{\mathtt{\,\times\,}}{\mathtt{8.05}}\right)}} = {\mathtt{759.605\: \!010\: \!502\: \!234\: \!142\: \!2}}$$

Rounding down, this is 759 whole pegs (and this assumes we can reshape the block as necessary!).

Note that 157.4 kg is 157400 g, and I've converted to grams because the density is in terms of grams/cm3, not kg/cm3.

Alan  Jul 11, 2014
Sort: 

1+0 Answers

 #1
avatar+26626 
+5
Best Answer

Volume of one cylindrical peg = pi*r2*L  where r is the radius and L is the length.

Here we have r = 0.5 inches = 0.5*2.54 cm = 1.27 cm,  and L = 2 inches = 2*2.54 cm = 5.08 cm

The volume of one peg = pi*1.272*5.08 cm3.

The mass of one peg is given by volume*density = pi*1.272*5.08 cm3 * 8.05 g/cm3 = pi*1.272*5.08*8.05 g

So the number of these you can get out of a block of mass 157.4kg is 154.7*1000/(pi*1.272*5.08*8.05)

$${\frac{{\mathtt{157\,400}}}{\left({\mathtt{\pi}}{\mathtt{\,\times\,}}{{\mathtt{1.27}}}^{{\mathtt{2}}}{\mathtt{\,\times\,}}{\mathtt{5.08}}{\mathtt{\,\times\,}}{\mathtt{8.05}}\right)}} = {\mathtt{759.605\: \!010\: \!502\: \!234\: \!142\: \!2}}$$

Rounding down, this is 759 whole pegs (and this assumes we can reshape the block as necessary!).

Note that 157.4 kg is 157400 g, and I've converted to grams because the density is in terms of grams/cm3, not kg/cm3.

Alan  Jul 11, 2014

23 Online Users

avatar
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details