8.24.Set Up:Let the rock initially be traveling to the right and take this to be the direction. The collisionoccurs over a short time interval and the light fixture acquires a small velocity so moves little during the collision.During the collision the wire remains nearly vertical and exerts little horizontal force on the fixture. Consider thecollision and the motion after the collision as separate events.Solve:Collision:There is no external horizontal force during the collision and This givesand Motion after the collision:At the maximum height reached by the fixture, all of the initial kinetic energy of the fix-ture is converted to gravitational potential energy. Conservation of energy givesand 8.25.Set Up:Apply conservation of momentum to the collision and the work-energy equation to the motion afterthe collision. Let be the direction the bullet was traveling before the collision.Solve:Motion after the collision:There is no change in height so The blockstops so and Let V
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