What is Ballistic pendulum: Definition and 68 Discussions

A ballistic pendulum is a device for measuring a bullet's momentum, from which it is possible to calculate the velocity and kinetic energy. Ballistic pendulums have been largely rendered obsolete by modern chronographs, which allow direct measurement of the projectile velocity.
Although the ballistic pendulum is considered obsolete, it remained in use for a significant length of time and led to great advances in the science of ballistics. The ballistic pendulum is still found in physics classrooms today, because of its simplicity and usefulness in demonstrating properties of momentum and energy. Unlike other methods of measuring the speed of a bullet, the basic calculations for a ballistic pendulum do not require any measurement of time, but rely only on measures of mass and distance.In addition its primary uses of measuring the velocity of a projectile or the recoil of a gun, the ballistic pendulum can be used to measure any transfer of momentum. For example, a ballistic pendulum was used by physicist C. V. Boys to measure the elasticity of golf balls, and by physicist Peter Guthrie Tait to measure the effect that spin had on the distance a golf ball traveled.

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  1. T

    Why Does Second Collision in Ballistic Pendulum Lead to Initial State?

    I was thinking about ballistic pendulums and the symmetry they exhibit. In the simplest case, you have one ball that begins at a certain height and collides with another ball at rest. You can calculate via conservation of momentum and energy the new velocities and max vertical displacements...
  2. Jenna

    Using Energy and momentum conservation to derive the equation

    Homework Statement I need to find the intial velocity of a ball, given the angle the pendulum bob swings through. I need to derive this equation. [/B] V0=4.43mtotalL1/2{1-cosΔθ}1/2/mball Homework EquationsThe Attempt at a Solution I have barely any attempts since I can't even think where to...
  3. U

    Muzzle Velocity by Analyzing Ballistic Pendulum

    Homework Statement Finding the equation for the muzzle velocity by using conservation of energy. 2. The attempt at a solution Ek+Eg=Ek2+Eg2 Well I'm 100% sure the kinetic energy of the ball is transferred into the catcher. The displacement is 1.9cm which is 0.019m. Mb=0.0077Kg (mass of ball)...
  4. jakec

    Momentum conservation (ballistic pendulum)

    Homework Statement A .01kg bullet is fired into a 1.2kg block hanging from a 1m wire. The bullet exits the block with a speed of 200m/s and the block swings to a height of .2 meters. What is the original velocity of the bullet? What percentage of the original energy of the bullet is no longer...
  5. D

    Linear momentum problem (ballistic pendulum)

    Homework Statement A ballistic pendulum is a device that may be used to measure the muzzle speed of a bullet. It is composed of a wooden block suspended from a horizontal support by cords attached at each end. A bullet is shot into the block, and as a result of the perfectly inelastic impact...
  6. Quadrat

    Conservation of linear/angular momentum in a ballistic pendulum

    I did a problem a coule of weeks ago with a vertical rod, frictionless hanging around the upper end, length L and mass m. Then a bullet with the same mass, m speed v is fired horizontally at the lowest point of the rod and becomes embedded in the rod. So I calculated the maximum angle it would...
  7. Quadrat

    Potential energy in a physical pendulum

    Hey PF! 1. Homework Statement If I have a pendulum; a vertically hanging rod with (length ##L## and mass ##m##) which can rotate freely about a point ##p## on the upper edge of the rod. Now I fire a bullet (also with mass ##m##) into it (strictly horizontal on the lower end of the rod). I...
  8. N

    How a Ballistic Pendulum works.

    Hello there. Recently I was tasked to design a lab experiment using a ballistic pendulum. Now I understand that all the sources of the internet say that by principle of conservation of linear momentum, (1/2)(m+M)V2 = (m+M)gh , or V2 = 2gh And then using principle of conservation of energy, we...
  9. terryds

    A Curious question About Ballistic Pendulum Solution

    I've watched a video about ballistic pendulum problems. The illustration is : I wonder why the final energy is just a gravity potential energy. I think there is also a rotational kinetic energy (since it will rotate and oscillate) Is my thought wrong?
  10. L

    Conservation of Energy Problem -- bullet fired into a ballistic pendulum

    Homework Statement A bullet has a mass of 7.5 g. It is fired into a ballistic pendulum. The pendulum's receiving block of wood is 2.5 kg. After the collision, the pendulum swings to a height of 0.1 m. What is the approximate velocity of the bullet? m_{bullet} = 7.5g = 0.0075 kg m_{wood} = 2.5...
  11. N

    How Does Trigonometry Determine the Height in a Ballistic Pendulum?

    Homework Statement Using trigonometry and Fig. 2 in the ballistic pendulum write-up, show that the height h the pendulum rises after capturing the ball is given by: h=R(1-cosθ) Figure two is here: http://imgur.com/W9nvVZT Homework Equations h=R(1-cosθ) The Attempt at a Solution...
  12. M

    Ballistic Pendulum initial velocity of bullet

    Homework Statement A ballistic pendulum is used to measure the speed of a bullet fired from a gun. The pendulum consists of a 20.0g block hanging from a string. A bullet, with mass 0.50gg, imbeds itself in the block causing the block to swing up to a height of 5.00cm. Find the speed of the...
  13. mesa

    Ballistic pendulum question

    This is a ballistic pendulum promlem, here is the scenerio that is outlined in my physics book: We have a wooden block of mass 1.20kg hanging from a massless rope 1.5m in length. A bullet of mass .01kg is fired at the block. The collision is inelastic but thermal losses from impact are...
  14. A

    LAB: Ballistic Pendulum + Conservation of Momentum

    I'm doing the prelab questions which require conceptual questions, not so much of math. The experiment is a typical ballistic pendulum lab - you'd shoot a paintball twoard a pendulum bob, and you measure the height the pendulum bob reaches after collision to calculate the related velocities...
  15. Y

    How Is the Initial Speed of a Projectile Calculated Using a Ballistic Pendulum?

    Homework Statement A ballistic pendulum is a common device that is designed to measure the speed of small projectiles. As shown in the sketch on the right, it is composed of an initially stationary metal "cage" which traps the projectile and is suspended vertically by a very light weight rod...
  16. J

    Ballistic pendulum, finding final height

    Homework Statement The Attempt at a Solution I used conservation of momentum for the initial velocity of mass 2, and conservation of mechanical energy for the movement from rest to highest position, KE=PE. The answer that I received is selected in the screenshot. However, when the...
  17. L

    Determining Velocity of Ball Fired Horizontally from Ballistic Pendulum

    I am trying to determine the velocity of a ball fired horizontally from ballistic pendulum. The data is as follows: ball mass: 62.2 g spring mass: 14.7 g rod mass: 89.3 g length of spring: 126.1 mm initial spring length: 5 cm compressed spring length: 1 cm k: 2.05 N/m calculated from...
  18. K

    Measuring Impact Velocity with a Ballistic Pendulum Prototype

    some device or contraption to measure point impact velocity - ballistic pendulum ? i hope you guys and gals can point me in the right direction for a prototype i am working on. I am looking for a device that measures impact velocity. much like a ballistic pendulum only much sturdier than the...
  19. QuarkCharmer

    Ballistic Pendulum results.

    Homework Statement I was just wondering if someone would be kind enough to look over these solutions and tell me if I am correct. The lab was a simple ballistic pendulum, which I am sure every physics student performs. Homework Equations The Attempt at a Solution 1.)...
  20. QuarkCharmer

    Ballistic Pendulum kinetic energy

    Homework Statement A 11.0 g rifle bullet is fired with a speed of 360 m/s into a ballistic pendulum with mass 9.00 kg, suspended from a cord 70.0 cm long. A.) Compute the initial kinetic energy of the bullet B.) Compute the kinetic energy of the bullet and pendulum immediately after the...
  21. P

    Calculating Energy Loss with Ballistic Pendulum

    Homework Statement How was energy lost while using the ballistic pendulum? Homework Equations Initial KE= 1/2mb*Vb^2 = 0.929J Final Potential graviational = (m+M)gh= 0.198J Energy loss = 0.929J - 0.198J= 0.731J The Attempt at a Solution I think the answer is: energy lost dues to...
  22. I

    Understand Momentum & Energy Conservation in Ballistic Pendulum Problems

    In solving a ballistic pendulum problem, you can break it up into two parts: (1) A bullet is fired and it lodges into a block. Momentum is conserved because there is no net external force. Energy is not conserved because there is friction between the block and bullet. (2) Once the bullet is...
  23. A

    Calculating Minimum Speed for Ballistic Pendulum with Attached Mass

    Homework Statement A uniform stick d = 1 m long with a total mass of 249 g is suspended vertically from a frictionless pivot at its top end. A wad of putty of mass 29 g is moving horizontally with speed v. It strikes and sticks to the stick at a distance 0.75 m from the pivot. What is the...
  24. C

    Ballistic Pendulum: Find the Bullet's Speed

    Homework Statement The ballistic pendulum is a block of 3.0 kg mass suspended from a thread 2.5 m long. A bullet with a mass of 9.0 g hits the block and sticks in it, the result being a deflection of the system by an angle of 18o. Homework Equations Find the bullet’s speed. The Attempt...
  25. J

    Understanding Elastic and Inelastic Collisions in Ballistic Pendulums

    Hey guys, I have some questions about this ballistic pendulum http://image.made-in-china.com/2f1j00nMvTZeBzkLoC/Ballistic-Pendulum.jpg My partner and me were discussing what kind of collision it made. I think it's an elastic since we placed a ball in the rod then pulled...
  26. D

    Ballistic Pendulum speed of a bullet

    Homework Statement The speed of a rifle bullet may be measured by means of a ballistic pendulum in the following way. The bullet, of known mass m and unknown speed v, embeds itself in a stationary wooden block of mass M, suspended as a pen- dulum of length L. This sets the block to...
  27. R

    Ballistic Pendulum and Projectile Lab

    Homework Statement I did a lab in physics where we used a ballistic pendulum. Basically we had to derive equations for the initial speed of the ball for the pendulum and as a projectile using energy/momentum and kinematics. I was just wondering what are some good sources of error for...
  28. C

    Solve Ballistic Pendulum Homework: Conservation of Energy & Momentum

    Homework Statement A 2.3 kg wood block hangs from the bottom of a 1.3 kg, 1.3 m long rod. The block and rod form a pendulum that swings on a frictionless pivot at the top end of the rod. A 12 g bullet is fired into the block, where it sticks, causing the pendulum to swing out to a 35 degrees...
  29. K

    Ballistic Pendulum - Kinetic Energy vs Gravitational Potential Energy

    Hello, I have been trying to get my head around the concepts of energy, work and momentum. I am trying to build some testing equipment to measure the "transfer of energy" of a moving object striking a pendulum type mass, but am unsure if my physics is correct. The image attached is my idea...
  30. G

    Ballistic Pendulum Problem: Determining Speeds of Bullet and Block

    Homework Statement I fire a bullet at a ballistic pendulum. The large block of wood has a mass M2 = 3.000 kg, and the bullet has a mass of m1 = 25.0 g. The bullet completely penetrates the wood and emerges with a speed of vf = 80.0 m/s. The wood, as part of a pendulum, swings up to a maximum...
  31. G

    Calculating % Kinetic Energy Conversion in Ballistic Pendulum

    Homework Statement A soft clay block is suspended so as to form a so-called ballistic pendulum. A bullet is fired point-blank into the block, imbedding itself therein and raising the latter to a height h. Derive an expression for the percentage of the kinetic energy converted into internal...
  32. V

    Ballistic pendulum change in kinetic energy problem

    Homework Statement a bullet of mass M is fired into a block of wood of mass m, the bullet sticks in the wood and causes it to swing upwards by height h calculate the change in kinetic energy from the bullet to the bullet+wood Homework Equations kinetic energy = 1/2MV^2 V = SQRT...
  33. B

    Ballistic Pendulum: Calculating Energy Transfer in a Suspended Wooden Block

    Homework Statement A bullet (mass m, velocity v) is fired into a suspended wooden block (mass M) which then rises up to height h with the bullet embedded within it. Find, in terms of m, M and H, the proportion of the initial kinetic energy of the bullet that is transferred to mechanical...
  34. N

    A bullet goes through a ballistic pendulum, what is it's initial velocity?

    Homework Statement A 7.0-g bullet is fired into a 1.5-kg ballistic pendulum. The bullet emerges from the block with a speed of 200 m/s, and the block rises to a maximum height of 12 cm. Find the initial speed of the bullet. Homework Equations Conservation of Momentum The Attempt at...
  35. B

    Change of KE in Ballistic Pendulum Collision

    Homework Statement Homework Equations mv=(m+M)v' KEi=1/2mv2 PE=KE (after collision) The Attempt at a Solution I'm am particularly stuck on part C although I'm not very confident in my first two answers either. a) 1/2(m+M)vf2=(M+M)gh vf2=2gh vf=SQRT(2gh) mv=(m+M)vf...
  36. J

    How Does Reduced Gravity on the Moon Affect a Ballistic Pendulum Experiment?

    Homework Statement How would doing this experiment in the moom effect the experiment ? "the experiment in lunching a ball against a pendulum and making an inelastic collision find the kenitic engergy and the inital velocity" Homework Equations I found all the answers and I assume the...
  37. S

    What is the equation to solve for muzzle speed in a ballistic pendulum problem?

    Homework Statement During a summer internship with a company, you devised the following method of measuring the muzzle speed of a high-powered rifle, as shown in the figure. You fire a bullet into a rod of mass 5.5 kg and length 150 cm that is free to rotate about the pivot at the top. The...
  38. S

    Solve Ballistic Pendulum Height Problem

    [solved]Ballistic pendulum Homework Statement A bullet of mass m = 0.024 kg is fired with a speed of vi = 97.00 m/s and hits a block of mass M = 2.61 kg supported by two massless strings. The bullet emerges from the right side of the block with a speed of vf = 48.50 m/s. Find the height to...
  39. S

    Bullet Through Ballistic Pendulum- Please help me

    1. A 9.05- g bullet from a 9-mm pistol has a velocity of 331.0 m/s. It strikes the 0.705- kg block of a ballistic pendulum and passes completely through the block. If the block rises through a distance h = 19.47 cm, what was the velocity of the bullet as it emerged from the block? i know that...
  40. N

    What is the speed of the bullet in a ballistic pendulum collision?

    Homework Statement A 16g bullet is fired into the bob of a ballistic pendulum of mass 1.5kg When the bob is at its maximum height, the strings make an angle of 60 degree with the vertical. The length of the pendulum is 2.3 m. Find the speed of the bullet. Homework Equations pi=pf...
  41. S

    Ballistic Pendulum calculation

    Homework Statement So does anyone here know a lot about ballistic pendulums? I was just wondering how I could calculate the distance the ball will travel horizontally when shot horizontally, from a table. Homework Equations The Attempt at a Solution I know that first, I have to...
  42. T

    Ballistic Pendulum Rifle: Solving for Post-Collision Height

    The problem: https://tycho-s.phys.washington.edu/cgi/courses/shell/common/showme.pl?courses/phys121/autumn08/homework/06/IE_algebra_ballistic_pendulum_MOM/pic.gif A rifle bullet of mass m = 0.03 kg traveling at vb = 240 m/s collides with and embeds itself in a pendulum of mass M = 2.88...
  43. J

    Ballistic Pendulum and Arrow

    So, I need to find the velocities of two arrows but I don't know what formulas to use. Can anyone point me in the right direction? http://img247.imageshack.us/img247/9376/okjen2.jpg
  44. R

    Ballistic Pendulum Bullet

    Homework Statement A 7.0-g bullet is fired into a 1.5-kg ballistic pendulum. The bullet emerges from the block with a speed of 200 m/s, and the block rises to a maximum height of 12 cm. Find the initial speed of the bullet. Now I think this is an imperfect inelastic collision because the...
  45. N

    Help on Ballistic Pendulum Angle

    Homework Statement A bullet (m = 0.029kg) is fired with a speed of 95.00m/s and hits a block (M = 2.40kg) supported by two light strings , stopping quickly. Find the height to which the block rises. The correct answer is 6.56E-02 m BUt the next question is: Find the angle (in...
  46. A

    Calculate Swing Length of Ballistic Pendulum | 25-gm Bullet at 300m/sec

    a 25-gm bullet traveling with a speed of 300m/sec strikes the block of a ballistic pendulum. the block weighs 98N and is supported by a light cord 1 m long. calculate the length of the arc through which the pendulum swings.
  47. U

    Determine Initial Velocity of Projectile with Ballistic Pendulum

    The ballistic pendulum is a block with the mass 2.50kg suspended on a cable, the projectile has a mass of 0.010kg and is shouted with the initial velocity, after the collision the pendulum reach the height of h=0.65 m/s. Determine the initial velocity of the projectile.
  48. C

    How Fast Was the Bullet That Hit the Pendulum?

    A 12.5 g bullet is shot into a ballistic pendulum that has a mass of 2.37 kg. The pendulum rises a distance of 9.55 cm above its resting position. What was the speed of that bullet? m(bullet) = 0.0125 kg m(pendulum) = 2.37 kg h = 0.0955 m I know that I'm supposed to use conservation of...
  49. R

    Ballistic Pendulum: Bullet Impact at 500m/s

    Homework Statement a ballistic pendulum is hit by a bullet traveling 500m/s , the ballistic pendulum is a block of wood hanging from a string. the block of wood (1kg) is hanging from the string of 2.5m the bullet has mass .006kg @ 500m/s the bullet passes right through the block of wood...
  50. I

    Compound ballistic pendulum

    Hello. I am doing a ballistic pendulum lab, and I have gotten stuck at a preparatory exercise. The problem is that the pendulum must be treated as a compound pendulum and not a simple pendulum. Homework Statement We have a compound pendulum which is a metal rod of mass M suspended at some...