# A war-wolf or trebuchet is a device used duringthe...

A war-wolf or trebuchet is a device used duringthe Middle Ages to throw rocks at castles and now sometimes used tofling large vegetables and pianos as a sport. A simple trebuchet isshown in the figure. Model it as a stiff rod of negligible mass,3.40 m long, joining particles of mass59.0 kg and 0.120kg at its ends. It can turn on a frictionless, horizontal axleperpendicular to the rod and 13.0 cm fromthe large-mass particle. The rod is released from rest in ahorizontal orientation. (a) Find the maximum speed that the0.120 kg object attains.

(b) Select the statements that are nottrue.

1. The radius of larger mass circular path r1 = 0.13 m
The radius of the smaller mass m2 is r2 = 3.40 m - 0.13 m = 3.27 m
The initial kinetic and potential energies are zero.
According to conservation of mechanical energy we have
KEf + PEf = 0
0.5(I1?2 +I2?2) + (m2gr2 -m1gr1) = 0    .........1
The whole system looks like dumble so that we can write themoment of inertia as
I1 =m1r21 and   I2 = m2r22
Substituting in eq 1 and solving for ?, weget
? = ? ( 2(I1 -I2) / ( I1r1 +I2r2) )
Substitute values.
m2 =59.0 kg
m1= 0.120kg
r1 = 0.13 m
r2 = 3.27m