(adsbygoogle = window.adsbygoogle || []).push({}); bullet and pendulum bob....initial speed...help! momentum.

1. The problem statement, all variables and given/known data

An 7.0 g bullet is fired into a 3.5 kg pendulum bob initially at rest and becomes embedded in it. If the pendulum rises a vertical distance of 8.0 cm, calculate the initial speed of the bullet.

________m/s

2. Relevant equations

well there's many ways to do it, but heres one way:

v=sqrt((1+M/m)*2gh)

i tried it another way too, and got the same answer that i did with the above equation

3. The attempt at a solution

so first, 7g bullet = .007kg bullet and height of 8cm = .08m

ok so then v=sqrt((1+3.5/.007)*2*9.8*.08) = ~28.03 m/s

now, i tried this TWO WAYS and got the same answer.

but webassign says it's wrong.

why?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Bullet and pendulum bob initial speed help! momentum.

**Physics Forums | Science Articles, Homework Help, Discussion**