Bullet acceleration homework problem

[kmikias]

Hi..guys i have question again i guess you gone help me out here is the question

1. A bullet of mass 0.0016 kg moving at 535m/s impacts a large fixed block of wood and travel 5.9 cm before coming to rest.
Assuming that the acceleration of the bullet is constant ,find the force exerted by the wood on the bullet. answer in units of KN.

here is what i did .
change cm to m.
then I try to find acceleration using the v^2 = v^2 + 2ah

after i found the acceleration i plug to F = ma
change N to KN.

but my answer was wrong ...

 

[alphysicist]

Hi kmikias,

Hi..guys i have question again i guess you gone help me out here is the question

1. A bullet of mass 0.0016 kg moving at 535m/s impacts a large fixed block of wood and travel 5.9 cm before coming to rest.
Assuming that the acceleration of the bullet is constant ,find the force exerted by the wood on the bullet. answer in units of KN.

here is what i did .
change cm to m.
then I try to find acceleration using the v^2 = v^2 + 2ah

after i found the acceleration i plug to F = ma
change N to KN.

but my answer was wrong ...

What numbers did you use, and what answer did you get?

 

[baba89]

Hi there,

Based on your description, it seems like you are on the right track with your approach. However, there may be some errors in your calculations that are leading to an incorrect answer. Here is a step-by-step guide on how to solve this problem and find the force exerted by the wood on the bullet:

1. First, let's convert the distance traveled from centimeters to meters. 5.9 cm is equal to 0.059 m.

2. Now, we can use the kinematic equation v^2 = u^2 + 2as to find the acceleration (a) of the bullet. Here, u is the initial velocity (535 m/s) and v is the final velocity (0 m/s). Plugging in the values, we get:

0^2 = (535)^2 + 2a(0.059)

Solving for a, we get a = -48144.068 m/s^2. Note that the negative sign indicates that the bullet is decelerating.

3. Next, we can use the equation F = ma to find the force exerted by the wood on the bullet. Here, m is the mass of the bullet (0.0016 kg) and a is the acceleration we just calculated (-48144.068 m/s^2). Plugging in the values, we get:

F = (0.0016)(-48144.068) = -77.031 KN

Note that the force is negative because it is acting in the opposite direction of the bullet's motion.

4. Finally, let's convert the force from Newtons to kilonewtons. 1 kN is equal to 1000 N, so we can simply divide the force by 1000 to get the final answer in KN:

F = -77.031/1000 = -0.077031 KN

So, the force exerted by the wood on the bullet is approximately 0.077 KN. Keep in mind that this answer may differ slightly from yours due to rounding errors or other factors. I hope this helps!