Question

A wooden block of mass 2 kg is resting on a smooth floor. A bullet of mass 100 gram moving with speed 500 metre/second strikes the blocks in get fixed in it and both start moving together. calculate the combined speed of bullet and block.


I actually got the answer wrong. My solution is in the photo on top. ​

Answer 1

Explanation:

Your answer is wrong because mass of box is taken as 2 kg but you have to take mass of box =2kg +mass of bullet. The reason is that box will start moving after bullet strike the box

Answer 2

solution :

mass of wooden block (m1) = 2kg

u1 of the wooden block = 0m/s

mass of the bullet(m2) = 100gm = 0.1kg

u2 of the bullet = 500m/s

their final velocity is not given

so,

let their combined velocity be V

(m1u1) + (m2u2) = (m1 + m2) * V

(2*0) + (0.1*500) = (2 + 0.1)* V

0 + 50 = 2.1 * V

V = 50/2.1 = 23.80m/s

hope it will help you.................

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