Question

A rock has a mass of 0.3kg. While being swung in a sling the rock has an angular momentum of 8.1kg*m2/s. When the rock is released, it has a height of 2.2m. At this moment the rock it traveling horizontally. The rock lands 24m from where it was launched. How long was the sling? Express your answer in meters.

Answer 1

Mass of rock = $0.3 kg$

Angular momentum = $8.1 kgm2/s$

Height = $2.2 m$

Distance = $24 m$

$\because$ Angular momentum = $iw$

$w= v/r$

$v^2= u^2+2as$

$v^2= 0^2+2(9.8×2.2)$

$v^2= 43.12$

$v= 6.566 ml$

Therefore $w= 6.566/24 =0.2736 rad/s$

$8.1=i (0.2736)$

$i=8.1/0.2736 =29.605 m$

The sling was $29.605 m$