# Physics: Rotational Motion

A 0.005kg bullet travelling horizontally with a speed of 1000m/s enters an 18kg door, embedding itself 10cm from the side opposite the hinges as in figure. The 1m wide door is free to swing on the hinges.

a) Before it hits the door, does the bullet have angular momentum relative the door’s axis of rotation? Explain.

b) Is mechanical energy conserved in this collision?

c) If the door opens immediately after collision, calculate the angular speed the door swing. The door has the same moment of inertia as a rod with axis at one end.

d) Calculate the energy of the door-bullet system and determine whether it is less or equal to the kinetic energy of the bullet before collision.

1. 👍
2. 👎
3. 👁
1. d) Calculate the energy of the door-bullet system and determine whether it is less or equal to the kinetic energy of the bullet before collision.

1. Of course m * R x V = .005 * .9 * 1000
2. No reason it should be, heat generated when bullet strikes. However Angular momentum does not change.
3. I am going to ignore the I of the bullet after collision which is .005*.81
so
.005 * .9 * 1000 = I w = (1/3)18(1)^2 w^2
So w = 0.866 radians/second

1. 👍
2. 👎
2. I think you can do (1/2) m v^2 and (1/2) I w^2

1. 👍
2. 👎

## Similar Questions

1. ### Physics

A 0.006-kg bullet traveling horizontally with a speed of 1.00 103 m/s enters an 21.1-kg door, imbedding itself 10.4 cm from the side opposite the hinges as in the figure below. The 1.00-m-wide door is free to swing on its hinges.

2. ### physics

as shown in the figure a bullet of mass 0.010 kg moving horizontally suddenly strikes a block of wood of mass 1.5 kg that is suspended as a pendulum. The bullet lodges in the wood, and together they swing upward a vertical

3. ### PHYSICS HELP!!!!!

A 7.0 g bullet is fired horizontally into a 1.5 kg block of wood suspended by a thread. The bullet emerges from the block with a speed of 195 m/s, and the block rises to a maximum height of 12 cm. Find the initial speed of the

4. ### 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

1. ### College physics

A 0.006 00-kg bullet traveling horizontally with a speed of 1.00 x 10^3 m/s enters an 20.1-kg door, imbedding itself 10.9 cm from the side opposite the hinges as in the figure below. The 1.00-m wide door is free to swing on its

2. ### Physics

A 15-g bullet is fired horizontally into a 3.000-kg block of wood suspended by a long cord. The bullet sticks in the block. Compute the speed of the bullet if the impact causes the block to swing 10 cm above its initial level.

3. ### Physics

A bullet with mass 4.91 g is fired horizontally into a 1.981-kg block attached to a horizontal spring. The spring has a constant 6.25 102 N/m and reaches a maximum compression of 6.38 cm. a) find the initial speed of the

4. ### Physics

a 100 gram bullet is fired from a 10 kg gun with a speed of 1000m/sec. what is speed of recoil

1. ### 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

2. ### Physis

A bullet of mass of 30g and travelling at a speed of 200msˉ¹ embeds itself in a wooden block. The bullet penetrates a distance of 12cm into the wood. Using the concepts of work done by a force and kinetic energy, determine the

3. ### Physics

A 3.5 g bullet is fired horizontally at 2 blocks resting on a smooth tabletop. The bullet passes trough the 1st block, with mass 1.2 kg and embed itself in the second with mass 1.8 kg. Speeds of 0.63 m/s and 1.4 m/s, respectively

4. ### Physics

A bullet of mass is fired horizontally with speed at a wooden block of mass resting on a frictionless table. The bullet hits the block and becomes completely embedded within it. After the bullet has come to rest within the block,