In a ballistic pendulum an object of mass m is fired with an initial speed at a
ID: 1287358 • Letter: I
Question
In a ballistic pendulum an object of mass m is fired with an initial speed at a pendulum bob. The bob has a mass M, which is suspended by a rod of length L and negligible mass. After the collision, the pendulum and object stick together and swing to a maximum angular displacement 6 as shown (Figure 1).Find an expression for Vo, the initial speed of the fired object. Express your answer in terms of some or all of the variables m, M, L, and 9 and the acceleration due to gravity, g. An experiment is done to compare the initial speed of bullets fired from different handguns: a 9.0 mm and a .44 caliber. The guns are fired into a 10-kg pendulum bob of length L. Assume thatExplanation / Answer
mvo = (M+m)*V
V = mvo/(M+m)
KE = PE
0.5*(M+m)*V^2 = (M+m)*g*L*( 1 - costheta )
0.5*V^2 = g*L*( 1 - costheta )
0.5*m^2*vo^2/(M+m)^2 = g*L*( 1 - costheta )
vo = sqrt(2*g*L*( 1 - costheta ))*(M+m)/m
B) ratio = 0.86