A ballistic pendulum experiment is performed.?

Question

The bullet is fired at a block while the block is at rest (the block is at the lowest swing point). Once the bullet hits the block it rises to its highest point swing. The maximum height the pendulum rises is 3cm, at this max height the pendulum subtends an angle of 36.9 degress. The mass of the bullet is 80g and the mass of the pendulum bob is 911g. Acceleration of gravity is 9.8m/s^2. What is the initial speed of the projectile(answer in units of m/s)?

Answer 1

Kinetic energy of the bullet does work on the pendulum and is completely converted to potential energy when the pendulum reached the top of its swing. The potential energy is mgh = (.911+.08)*9.8*.03 = 0.261954J. So the initial Ke of the bullet was 0.261954J=.5*m*v² = .5*.08*v² or v = 2.559 m/s.

Doug