A bullet traveling at a speed of 650 m / s has a temperature of 75 ° C. She falls into a snowdrift and gets stuck in it.

| March 27, 2021 | education

A bullet traveling at a speed of 650 m / s has a temperature of 75 ° C. She falls into a snowdrift and gets stuck in it. Snow temperature in a snowdrift is 0 ° C. At the same time, 6.5 g of snow melts and turns into water with a temperature of 0 ° C. Find the mass of the bullet. Consider the specific heat of melting of snow to be 3.4 * 10 ^ 5 J / kg. And the specific heat capacity of lead is 130 J / (kg · ° C).

Data: V (bullet speed before hitting the snow) = 650 m / s; t1 (initial temp. bullet) = 75 ºС; t2 (temperature of snow in a snowdrift, temperature of received water) = 0 ºС; m2 (mass of melted snow) = 6.5 g = 0.0065 kg.

Constants: λ (heat of melting of snow) = 3.4 * 10 ^ 5 J / kg; Сс (heat capacity of lead) = 130 J / (kg * ºС).

We express the required bullet mass from the equality: m1 * V ^ 2/2 + Cc * m1 * (t1 – 0) = λ * m ^ 2, whence m1 = λ * m ^ 2 / (V ^ 2/2 + Cc * ( t1 – 0)).

Calculation: m1 = 3.4 * 10 ^ 5 * 0.0065 / (650 ^ 2/2 + 130 * (75 – 0)) = 0.01 kg.



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