A calastic pendulum. The height is related to the speed of the bullet-block system according to the conservation of energy. The speed Vf can be found using the conservation of momentum during the inellastic collistion of the bullet and apple.

Look at the following diagrahm to see how its possible.

In the picture above here's what the abbreviations represent.

• Vli = velocity of bullet
• Vf = velocity of bullet and Apple
• M1 = mass of bullet
• M2 = mass of apple
• Ki = Kinetic Energy due to the bullet
• Kf = Kinetic Energy of the apple and bullet
• h = change in height of apple
• g = acceleration due to gravity

Using the diagrams above predict the height of the apple if 25 gram bullet traveling at 300 m/s and hits a 75 gram apple.

Was the law of conservation of energy observed? Show your calculations to support this.

Images courtesy of "Physics" For Scientist and Engineers, Third Edition, by Paul A Tipler & Worth Publ. Copywright1991

back to Physics Classroom