At what speed should a piece of ice with a temperature of 0C move so that when it hits a stone wall, it completely melts.

To calculate the required speed of a piece of ice, we use the equality: λ * m = m * V ^ 2/2, whence we express: V = √ (2 * λ).

The value of the constant: λ is the specific heat of melting of ice (λ = 3.4 * 10 ^ 5 J / kg).

Let’s make the calculation: V = √ (2 * λ) = √ (2 * 3.4 * 10 ^ 5) = 824.6 m / s.

Answer: Before hitting a stone wall, a piece of ice had to move at a speed of 824.6 m / s.