4) A bullet of mass 12 grams is fired into a large block of mass 1.5 kg suspended from light vertical wires. The bullet imbeds in the block and the whole system rises 10 cm. Find the velocity of the bullet just before collision.

Question

4)	A bullet of mass 12 grams is fired into a large block of mass 1.5 kg suspended from light vertical wires. The bullet imbeds in the block and the whole system rises 10 cm. Find the velocity of the bullet just before collision.

anonymous · Answer

m=.012 kilograms
M=1.5 kilograms
Height= 0.1meters
find velocity BEFORE collision

anonymous · Answer

loss in kinetic energy = gain in potential energy

0.5mv^2 - 0   =    mg(h+0.1) - mgh

this should do it. but i'm not sure about it.

anonymous · Answer

how bout using the formula of conservation of momentum or conservation of energy?

anonymous · Answer

conservation of momentum will be hard to utilize cause we can't figure out the total momentum after collision. but we are provided here with the increase in potential energy after the collision so using conservation of energy is better .

noelgreco · Answer

You don't need to calculate the total momentum after the collision.

You need 2 separate equations.

Since momentum is conserved even in inelastic collisions such as this,

mv = (m + M) v'  where m is the mass of the bullet, M is the mass of the block, v is the velocity of the bullet, and v' is the velocity of the bullet and block an instant after the collision.  That's the first equation.