Question

A steel ball radius of4 cm is moving with the speed of 81 CMS^-1 collides elasticali with another steel ball or radius 2 cm which is in rest condition what are there final velocities after collision

Answer 1

Answer:

$m = \rho \: v = \rho \: \frac{4}{3}\pi {r}^{3} = k {r}^{3}$

Since p is same for both balls .

So mass of first ball will be

$= k( {4}^{3} ) = 64k$

Second ball

$= k( {2}^{3}) = 8k$

Use linear momentum conservation

Let final velocity be v .

$64k \times 81 + 0 = (64k + 8k)v \\ \\ v = 81 \times \frac{64k}{72k} = 64 \: \frac{cm}{s}$

Answer 2

Answer:

as the collision is elastic apply linear momentum and conservation of Kinetic Energy