physics

As shown in the diagram, a bullet of mass 7.0 g strikes a block of wood of mass 2.1 kg. The block of wood is suspended by a string of length 2.0 m, forming a pendulum. The bullet lodges in the wood, and together they swing upward a distance of 0.40 m from the original position of the wood block. What was the speed of the bullet just before it struck the wooden block?

  1. 👍
  2. 👎
  3. 👁
  1. bullet mass + wood mass = 2.107 kg

    potential energy if up 0.4 meter:

    I assume this is along the circumference
    so
    .4 = theta * 2 =
    theta = .2 radians = 11.5 degrees

    distance up from bottom = 2 (1-cos theta)
    = .0803 meters

    so energy at top = m g h =2.107*9.81*.0803 = 1.66 Joules

    that is its kinetic energy at the bottom
    (1/2) m v^2 = 1.66
    .5*2.107*v^2 = 1.66
    v = 1.26 m/s

    momentum of block with bullet
    = 2.107 * 1.26 = 2.64 kg m/s

    that was the bullet momentum before the crash
    .007 v = 2.64
    v = 378 m/s

    1. 👍
    2. 👎
  2. no

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics

    1. A bullet of 0.0500 kg is fired into a block of wood. Knowing that the bullet left the gun with a muzzle velocity of 350. m/s, and the bullet penetrates .15 m into the block of wood, determine: a) The average force required to

  2. Physics

    A 2.50g bullet, traveling at a speed of 425m/s, strikes the wooden block of a ballistic pendulum. The block has a mass of 270g (a) find the speed of the bullet/block combination immediately after the collision (b) how high does

  3. Physics (6)

    A 10-g bullet moving 1000 m/s strikes and passes through a 2.0-kg block initially at rest, as shown. The bullet emerges from the block with a speed of 400 m/s. To what maximum height will the block rise above its initial position?

  4. physics

    a bullet of mass 120g is fired horizontally into a fixed wooden block with a speed of 20 m/s. If the bullet is brought to rest in the block in 0.1s by a constant resistance, calculate the 1) magnitude of the 2) Distance moved by

  1. Physics- Ballistic pendulum

    A simple pendulum is made from a 2 kg. block of wood suspended from a light cord of length 1 m. When the pendulum is hanging in such a way that it is stationary and vertical, a bullet is shot horizontally into the block of wood

  2. physics

    A ballistic pendulum consists of a 1.25-kg block of wood that is hanging from the ceiling in such a way that when a bullet enters it, the block’s change in height can be recorded as it swings. A bullet having a mass of

  3. PHYSICS

    A 15g bullet is fired horizontally into a block of wood with a mass of 2.5 k and embedded in the block. Initially the block of wood hangs vertically and the impact causes the block o swing so that its center of mass rises 15cm.

  4. Physics

    A small wooden block with mass 0.800kg is suspended from the lower end of a light cord that is 1.52m long. The block is initially at rest. A bullet with mass 0.0126kg is fired at the block with a horizontal velocity v0. The bullet

  1. physics

    A .22 rifle bullet traveling at 360m/s strikes a block of wood, which penetrates to a depth of .110m. The mass of the bullet is 1.80g. Assume a constant retarding force.A) how much time is required for the bullet to stop? b) what

  2. physics

    An 8.0 g bullet is fired horizontally into a 9 kg block of wood and sticks in it.The block,which is free to move,has a velocity of 40cm/s after impact.Find the initial velocity of a bullet. You know the momentum (total mass) of

  3. physics

    A ballistics pendulum is a device used to measure the speed of a fast moving projectile such as a bullet. A bullet of mass 5g is fired into a large block of wood of mass 1.5kg suspended from some light wires. The bullet is stopped

  4. Physics

    A bullet of mass .03 kg moving with a speed of 400m/s penetrates 12cm into a fixed block of wood calculate the average force exerted by the wood on the bullet.

You can view more similar questions or ask a new question.