00:02
Hi, here in this given problem, mass of the rifle bullet, that is m is equal to 12 .0 gram, and its initial speed, vb, is equal to 380 meter per second.
00:30
Length of the cord that is given as 70 .0 centimeter or we can say this is 0 .70 meter.
00:50
In the first part of the problem we have to find height raised by this ballistic pendulum.
01:07
So to find that height raised, first of all, we have to find speed gained by ballistic pendulum.
01:13
When rifle bullet hits it to find it using conservation of linear momentum, linear momentum, initial momentum before collision momentum of the bullet that should be equal to final momentum of the pendulum, m plus m, the combined mass of pendulum along with the rifle bullet, multiplied by its speed vf so that vf will be given by m into vb divided by m plus m means this is 0 .012 kilogram multiplied by vb which is 380 divided by 0 .012 plus 9 kilogram mass of the ballistic pendulum is calculated to be equal to 0 .506 meter per second.
02:28
Now to find height raised by this pendulum using conservation of energy initial kinetic energy of the pendulum ballastic pendulum at its lowest position half m plus m into v f square that should be equal to its gravitational potential energy at the highest point.
03:00
Cancelling this m plus m, an expression for h will be vf square by 2g...