Question

A bullet of mass 25 g is fired horizontally into a ballistic pendulum of mass 5.0 kg and gets embedded in it (figure 9-E14). If the center of the pendulum rises by a distance of 10 cm, find the speed of the bullet.

Answer 1

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ANSWER::

Mass of bullet , m = 25 g = 0.025 kg

Mass of pendulum = 5 kg

Vertical displacement , h = 10 cm = 0.1 m

Let it strike pendulum with velocity u.

Let final velocity be v

mu = (M + m)v

v = mu / (M + m) = 0.025 x u / 5.025 = u / 201

Using conservation of energy ,

0 - (1/2) (M + m) V² = - ( M + m) g x h

u² / (201)² = 2 x 10 x 0.1

u = 201 x √2

u = 280 m/s

Hope it helps!