# Solving for Impact Velocity: A Bullet of Ice at 0°C

• noobatphysics
In summary, the question is asking for the impact velocity needed to melt 68% of a bullet of ice at 0 degrees Celsius, assuming all the impact energy is retained by the ice. The solution involves using the equations 1/2mv^2 and Q=ml, and equating them to find the value of v. However, since only 68% of the mass melts, the kinetic energy must equal 0.68ml. The correct answer is approximately 674 m/s.
noobatphysics

## Homework Statement

A Bullet of ice at a temperature of 0 degrees celieus is fired into a target
Assuming that all the impact energy is retained by the ice
what impact velocity is needed to melt 68% of the ice

1/2mv^2
Q = ml

## The Attempt at a Solution

i got..
v^2 = 668000
i doubt that is the correct answer
can some show me the steps to work this out

Why didn't you use the 68%? The kinetic energy turns into the energy needed to melt 0.68m, not m.

um I am still puzzled
LOL
can u show me the steps?

I thought you used:

1/2mv^2
Q = ml

and equated them to get:

1/2mv^2=ml
v^2=2l

The statement 1/2mv^2=ml means "all the kinetic energy turns into the energy needed to melt the mass". However, only 68% of the mass melts, so the kinetic energy has to equal 0.68ml.

oh i see...

i got... 674 m/sec

doesn't seem right

Ek = 334800 x .68?

## 1. What is the equation for calculating impact velocity?

The equation for calculating impact velocity is V = √(2gh), where V is the impact velocity, g is the acceleration due to gravity, and h is the height from which the object is dropped.

## 2. How does the temperature of the bullet of ice affect its impact velocity?

The temperature of the bullet of ice does not affect its impact velocity as long as it remains at 0°C. This is because the impact velocity is determined by factors such as gravity and height, rather than the temperature of the object.

## 3. Is there a difference in impact velocity between a bullet of ice and a bullet of the same size made of another material?

Yes, there will likely be a difference in impact velocity between a bullet of ice and a bullet made of another material. This is because the mass and density of the material can affect its acceleration due to gravity and therefore impact velocity.

## 4. What other factors can impact the impact velocity of a bullet of ice?

Other factors that can impact the impact velocity of a bullet of ice include air resistance, wind speed, and the shape and size of the object.

## 5. How can knowing the impact velocity of a bullet of ice be useful in real-life situations?

Knowing the impact velocity of a bullet of ice can be useful in understanding the potential damage it can cause upon impact. This information can be used in areas such as forensic science, ballistics, and safety measures for ice-related activities.

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