Ballistics Test: Calculating Time, Force & Speed

In summary, the ballistics test involved a 25.0 bullet traveling horizontally at 1100, going through a 20.0-thick 450 stationary target and emerging with a speed of 800. The target is free to slide on a smooth horizontal surface. To find the time the bullet is in the target, one could use the impulse equation or sketch a v vs t graph to find the area and calculate a formula. The average force exerted by the bullet on the target was found to be 35714.286. Finally, to find the target's speed just after the bullet emerges, one could use the impulse equation and the action/reaction principle, taking into account the target's mass.
  • #1
julz3216
18
0

Homework Statement


In a ballistics test, a 25.0 bullet traveling horizontally at 1100 goes through a 20.0 -thick 450 stationary target and emerges with a speed of 800 . The target is free to slide on a smooth horizontal surface.
a.How long is the bullet in the target?
b. What average force does the bullet exert on the target?
c. What is the target's speed just after the bullet emerges?


Homework Equations



p=mv
impulse= F*change in time
F=ma

The Attempt at a Solution



I have no idea how to do part a.
I used the impulse equation for b but got the wrong answer.
For c, I think I use the impulse equation and then calculate vf from the kinetics equation?
 
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  • #2
Part (a) is a bit tricky. You probably don't have a formula that is perfect for the job, containing Vi, Vf, d and t. May have to use one equation to find the acceleration, then another one to find the time.

Alternatively, you could sketch the v vs t graph from 0 to t, showing the initial and final v.
The distance is the area under this graph - a trapezoid. Using this, you could make your own formula relating Vi, Vf, d and t. Or put the numbers on the graph and just find the time geometrically, using the area formulas.
 
  • #3
ok so i got a and b

a. t=.00021
b. average force = 35714.286

but I still don't know how to get part c...I thought maybe it would be 300 because that is the speed the bullet lost in the target but that is wrong.

any help??
 
  • #4
Doesn't b) give you the average force on the target?

You know that action/reaction thing?

The target's mass is what?
 
  • #5
In the future can you please provide the units your problems are in?

Units matter.
 

1. What is the purpose of conducting a ballistics test?

A ballistics test is performed to analyze the performance of a firearm or ammunition, and to gather information about its velocity, trajectory, and impact force. These tests are essential for determining the accuracy and effectiveness of a firearm or ammunition.

2. How is time calculated in a ballistics test?

Time is calculated in a ballistics test by measuring the time it takes for a projectile to travel a known distance. This can be done using high-speed cameras or specialized measuring devices. The time is then used to calculate the velocity and trajectory of the projectile.

3. What factors affect the force of impact in a ballistics test?

The force of impact in a ballistics test is affected by various factors such as the weight and velocity of the projectile, as well as the type of target material. Other factors that can influence impact force include the angle of impact, wind speed, and atmospheric conditions.

4. How is speed measured in a ballistics test?

Speed is measured in a ballistics test by using a chronograph, which is a device that uses sensors to measure the time it takes for a projectile to travel a specific distance. The speed is then calculated by dividing the distance by the time.

5. What are the applications of ballistics testing?

Ballistics testing has various applications, including forensic investigations, military and law enforcement training, and product development for firearms and ammunition. It is also used in sports such as hunting and shooting competitions to evaluate the performance of different firearms and ammunition.

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