Problem Solving Momentum Impulse and Conservation of Momentum

Problem Solving: Momentum, Impulse, and Conservation of Momentum 8. 01 W 06 D 3

Today’s Reading Assignment: W 06 D 3 Young and Freedman: 8. 1 -8. 5

Group Problem: Exploding Projectile An instrument-carrying projectile of mass m 1 accidentally explodes at the top of its trajectory. The horizontal distance between launch point and the explosion is x 0. The projectile breaks into two pieces which fly apart horizontally. The larger piece, m 3, has three times the mass of the smaller piece, m 2. To the surprise of the scientist in charge, the smaller piece returns to earth at the launching station. Neglect air resistance and effects due to the earth’s curvature. Use conservation of momentum and kinematics to find how far away, xf, from the original launching point does the larger piece land? 3

Group Problem: Acrobat and Clown An acrobat of mass m. A jumps upwards off a trampoline with an initial y-component of velocity vy, 0 = v 0. At a height h 0, the acrobat grabs a clown of mass m. B. Assume the acrobat grabs the clown during a time interval that is negligibly small. a) What is the velocity of the acrobat immediately before grabbing the clown? b) What is the velocity of the acrobat immediately after grabbing the clown? c) How high do the acrobat and clown rise?

Gr. Prob. : Ballistic Pendulum A simple way to measure the speed of a bullet is with a ballistic pendulum, which consists of a wooden block of mass m 1 into which a bullet of mass m 2 is shot. The block is suspended from two cables, each of length L. The impact of the bullet causes the block and embedded bullet to swing through a maximum angle φ. a) Find an expression for the initial speed of the bullet as a function of m 1, m 2, L, g, and φ. b) Determine the ratio of the lost mechanical energy (due to the collision of the bullet with the block) to the initial kinetic energy of the bullet.

Next Reading Assignment: W 07 D 1 Young and Freedman: 8. 3 -8. 4