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

A 18.00 Kg lead sphere is hanging from a hook by a thin wire 3.80 m long, and is free to swing in a complete circle. Suddenly it is struck horizontally by a 4.50kg steel dart that embeds itself in the lead sphere.

a)What must be the minimum initial speed of the dart so that the combination makes a complete circular loop after the collision

2. Relevant equations

v_{1}=(m_{s}+m_{d}/m_{d})v_{2}

3. The attempt at a solution

d=dart s=sphere

mdvd=(ms+md)v2

vd=(ms+md/md)v2

v2 makes a complete circular loop so

1/2(md+ms)v2^{2}=(md+ms)2gr

v2=sqrt(4gr)

vd=(ms+md/md)sqrt(4gr)

vd=(18+4.5/4.5)sqrt(4*9.8*3.8)

=5*12.204=61.02m/s

vd=61.02m/s

Now my problem with this is the TA said I took all the right steps to solve this equation but I'm still getting an error using masteringphysics and I have gone over my work for errors 10 times by now. Is the work I did correct or am I missing something in my calculations.

Thanks in advanced for any assistance.

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

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: Inelastic Collision of a dart

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