(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A stick of dynamite blows a boulder into 4 pieces. The boulder was stationary before the explosion. After the explosion, three of the pieces have the following momenta;

piece a = 10m/s West 1kg

piece b = 20m/s North 2kg

piece c = 10m/s East 4kg

Calculate the mass of the missing piece if the magnitude of its velocity is 25m/s

2. Relevant equations

Ptotal(initial)=Ptotal(final)

P=mv

3. The attempt at a solution

Since the boulder was not moving, its momentum is zero. The momentum of each piece is its mass x its velocity. Each piece's momentum added to each other will equal zero because momentum is conserved. So I get;

0=m1v1+m2v2+m3v3+m4v4

0=1kg(10m/s W)+2kg(20m/s N)+4kg(10m/s E)+m4(25m/s)

-90kgm/s=m4(25m/s)

m4=-3.6kg

Now I can't have a negative mass, so what can I do to solve this?

**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: Exploding boulder

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