Question

A 10-g bullet of unknown speed is shot horizontally into a 2-kg block of wood suspended from the ceiling by a cord. The bullet hits the block and becomes lodged in it. After the collision, the block and the bullet swing to a height 30cm above the original position. What was the speed of the bullet? (This device is called the ballistic pendulum). Take g=9.8ms^2

Answer 1

there is an energy conversion here can u figure out what?

Answer 2

i dont get you?

Answer 3

some type of energy is getting converted to some other
hint: talk about mechanical energy

Answer 4

tke the bullet+bloch+cord as the system.then all forces between them will be internal,the net external force on the system will be zero and u can use the principle of conservation of energy

Answer 5

in physics,thinhgs do not bloom out of nowhere so we consider what gets converted to what
if u have trouble guessing that
what are the 2 mechanical energy types available?

Answer 6

take areference line and accordingly frame the equation

Answer 7

@salini you mean motion energy and stored mechanical energy

Answer 8

yes ....come on go on what are they?

Answer 9

u mean kinetic energy b4 collision = kinectic enrgy after collision?

Answer 10

we have no idea abt the kinectic energy of BULLET after collision why?

Answer 11

it is an inelastic collision between the bullet and the block as the bullet gets embedded int the block,some heat is released so kinetic energy alone is not conserved

Answer 12

while doing these sums consider systems not individual particles of the system
total mechanical energy of system(wood+bullet) b4 collision=toatl mechanical energy of system after collision

Answer 13

again mechjanical energy of systm=sum of kinetic energy(by virtue of motion+potentail energy by virtue of height{here})