Question

10g bullet is fired into a 2.5kg ballistic pendulum and becomes embedded in it. If the pendulum raises a vertical distance of 8cm, calculate the initial speed of the bullet.

Answer 1

19.8m/s

Step-by-step explanation:

Total mass = m = 2.5kg + 10g = 2.5 + 0.01 = 2.51 kg

Height gained = h = 8cm = 0.08m

Gain in potential energy by pendulum + bullet = mgh = 2.51 * 9.8 * 0.08 = 1.96784 J

By conservation of energy, loss in kinetic energy of bullet = gain in potential energy by pendulum + bullet = 1.96784 J

`(1)/(2) mv^(2) = 1.96784`

m = 10 g = 0.01kg

v=
`\sqrt{(2*1.96784)/(0.01) }`

v = 19.8385 m/s = 19.8m/s approximately