What is the speed of the bullet fired into a wood block on a table?

In summary, a 10g bullet is fired into a 10kg wood block at rest on a wood table. The block slides 5.0cm and we need to determine the speed of the bullet. First, we need to find the frictional force between the block and table, which is given as 0.2. From there, we can determine the acceleration of the block and use that to find the initial velocity of the block just after impact. The momentum of the block with the bullet embedded must be the same as the momentum of the bullet before impact. However, the actual process may be more complicated due to the block starting to slide before the bullet stops penetrating. Thank you to olderdan for the helpful guidance.
  • #1
madness006
4
0
a 10g bullet is fired into a 10kg wood block that is at rest on a wood table. The block, with the bullet embedded, slides 5.0cm across the table. What was the speed of the bullet?

So my question is how do I get started, this problem has had me stuck for awhile. Thanks
 
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  • #2
Work backwards. First assume that the bullet+block lose all kinetic energy to friction. How much kinetic energy would it have had ?
 
  • #3
The problem does not contain all the information you need. Perhaps you are expected to look something up. The missing ingredient has to do with the friction between the block and the table.
 
  • #4
ok, the friction between wood and wood says its .2
 
  • #5
madness006 said:
ok, the friction between wood and wood says its .2
Use this information to determine the frictional force acting on the block as it slides the 5cm. From the force you can find the acceleration. From the acceleration and distance you can find the initial velocity of the block just after impact. The momentum of the block with imbedded bullet just after impact has to be the same as the bullet before impact (block initially at rest). The actual process is a bit more complicated because the block starts sliding before the bullet stops penetrating, but you can assume the bullet and block have the same velocity as soon as they touch.
 
  • #6
thanks olderdan, you helped me immensly.
 

1. What is momentum?

Momentum is a measure of an object's motion and is calculated by multiplying its mass by its velocity. It is a vector quantity, meaning it has both magnitude and direction.

2. How do I calculate momentum?

To calculate momentum, you can use the formula p = mv, where p is momentum, m is mass, and v is velocity. Ensure that the units for mass are in kilograms and velocity are in meters per second (m/s).

3. What is the law of conservation of momentum?

The law of conservation of momentum states that the total momentum of a closed system remains constant. This means that in a collision or interaction between objects, the total momentum before the interaction is equal to the total momentum after the interaction.

4. How does momentum relate to force?

Momentum and force are related through Newton's Second Law, which states that the net force acting on an object is equal to its mass multiplied by its acceleration. In other words, a change in momentum can be caused by a force acting on an object.

5. What are some real-life examples of momentum?

Some common examples of momentum in everyday life include a moving car, a bouncing basketball, a swinging pendulum, and a rolling bowling ball. In each of these examples, the object has both mass and velocity, resulting in momentum.

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