Question

How many spherical balls of 2.5 mm diameter each can be obtained by melting a semicircular dise
of diameter 7 cm, thickness 8 mm?
[Ans: 1882]​

Answer 1

Answer:

1882

Step-by-step explanation:

The semicircular dise has a diameter of 7 cm (given) and thickness 8 mm (given).  

So, it's radius (r) = 3.5 cm and thickness (t) =0.8 cm.

Now, it's volume V=$[\frac{1}{2}\pi r^{2}].t$

                              =$\frac{1}{2}* \frac{22}{7}*(3.5)^{2}*0.8$

                              =15.4 cm³

Now, each spherical ball has diameter 2.5 mm (given) i.e. radius (r) =0.125 cm.

So, it's volume (v) = $\frac{4}{3}.\pi r^{3}$

                             = $\frac{4}{3}*\frac{22}{7}*(0.125)^{3}$

                             = 0.00818 cm³

Therefore, number of spherical balls can be obtained = $\frac{V}{v}$

                                                                                         =$\frac{15.4}{0.00818}$

                                                                                          =1882.64 ≈1882 (Answer)