An 800 g bullet is fired into a 150 g block that is initiall

An 8.00 g bullet is fired into a 150 g block that is initially at rest at the edge of a table of 1.00 m height (Fig. P6.30). The bullet remains in the block, and after the impact the block lands d = 1.5 m from the bottom of the table. Determine the initial speed of the bullet.
1 m/s

Solution

block will leave table horizontally.

so initial speed of bullet+block is horizontal.

so initial vertical velocity uy = 0

block have to go down 1 m vertically. In vertical using

y = uy*t + ay*t

-1 = 0 - 9.81t^2 /2

t = 0.45 sec

block travels 1.5 m in 0.45 sec.

so speed = 1.5 / 0.45 = 3.32 m/s

now using momentum conservation of block and bullet system,

initial momentum of bullet + block = final momentum

0.008* u + 0.150*0 = 0.008*3.32 + 0.150*3.32

u = 65.57 m/s

initial speed = 65.57 m/s