# Final Velocity of 5.0g Bullet: 117m/s

• Ayesha Shafique
In summary, the conversation discusses the final velocity of a 5.0 g bullet starting from rest when a net force of 45 N is applied over a distance of 0.80 m. The solution involves using the formula F=ma to calculate the acceleration, and then using the formula d=1/2at^2 to determine the time taken. The final answer is 120m/s, but it is important to consider significant numbers in calculations.
Ayesha Shafique
What will the final velocity of 5.0 g bullet starting from rest if a net force of 45 N is applied over a distance of 0.80 m ?2.3. i tried to solve it but i don't know of my anwer is correct
F=ma, F/m=a
45/.005 kg
a=9000m/s^-2
From this formula ( d=1/2at^2) we can say that
Time= 2d/a and then take under root
2×0.80/9000 (under root or square root)
=0.013 sec
initial velocity (u) =0
a=v-u/t
at=v-u
9000×0.013=v-0
117+0=v

Last edited by a moderator:
You get 120m/s if you don't round down to 0.013 seconds.

CWatters said:
You get 120m/s if you don't round down to 0.013 seconds.
I don't understand what you mean by this. Please tell what does it mean because i am only in 8 grade

Ayesha Shafique said:
I don't understand what you mean by this. Please tell what does it mean because i am only in 8 grade

What CWatters means is that 0,013 s is not the exact value of the time. If you use the exact value, which is t = (2*0,8/9000)^(1/2), you will get a slightly different, more correct answer. I would recommend googleing "significat numbers". :)

CWatters
Alettix said:
What CWatters means is that 0,013 s is not the exact value of the time. If you use the exact value, which is t = (2*0,8/9000)^(1/2), you will get a slightly different, more correct answer. I would recommend googleing "significat numbers". :)
Thank you very much for your help. I also had the same answer but the problem was that i shortened 0.0133333333333 to 0.013 that's why my answer was 117 and not 120.

## 1. What is the formula for calculating final velocity?

The formula for calculating final velocity is vf = vi + at, where vf is the final velocity, vi is the initial velocity, a is the acceleration, and t is the time.

## 2. How do you convert grams to kilograms?

To convert grams to kilograms, divide the gram value by 1000. In this case, 5.0 grams would be equivalent to 0.005 kilograms.

## 3. What is the acceleration of a bullet?

The acceleration of a bullet is typically assumed to be constant and equal to the acceleration due to gravity, which is 9.8 m/s².

## 4. Is the final velocity affected by the mass of the bullet?

Yes, the final velocity is affected by the mass of the bullet. In this case, the final velocity of the 5.0g bullet is 117m/s. If the mass of the bullet were to change, the final velocity would also change.

## 5. How does air resistance affect the final velocity of a bullet?

Air resistance does not have a significant effect on the final velocity of a bullet. In ideal conditions, where air resistance is negligible, the final velocity would be equal to the initial velocity. However, in real-world scenarios, air resistance may slightly decrease the final velocity of a bullet.

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