Question

С какой наименьшей скоростью должна лететь свинцовая дробинка, чтобы при ударе о препятствие она расплавилась? Считать, что 80% кинетической энергии превратилось во внутреннюю энергию дробинки, а температура дробинки до удара была 127 °С.

Answer 1

n=Q/A*100%

Q=cmt

A=mV^2/2

n=2ct/V^2

V^2=2ct/n

V=корень 2ct/n=корень 2*140*(327-127)/0.8=264

Ответ:264

Answer 2

Minimum Speed for Lead Pellet to Melt on Impact

To determine the minimum speed at which a lead pellet must travel in order to melt upon impact, we need to consider the conversion of kinetic energy into internal energy and the change in temperature of the pellet.

Given: - Initial temperature of the pellet before impact: 127 °C - Percentage of kinetic energy converted into internal energy: 80%

To calculate the minimum speed, we can use the equation for kinetic energy:

Kinetic Energy = (1/2) * mass * velocity^2

Since we are looking for the minimum speed, we can assume that all the kinetic energy is converted into internal energy. Therefore, we can equate the kinetic energy to the change in internal energy:

Kinetic Energy = Change in Internal Energy

The change in internal energy can be calculated using the equation:

Change in Internal Energy = mass * specific heat capacity * change in temperature

In this case, the change in temperature is the final temperature of the pellet after impact minus the initial temperature.

Let's calculate the minimum speed using these equations.

First, we need to find the specific heat capacity of lead. According to source the specific heat capacity of lead is approximately 0.128 J/g°C.

Next, we need to find the mass of the lead pellet. Unfortunately, the mass of the pellet is not provided in the question. Therefore, we cannot calculate the minimum speed without this information.

Please provide the mass of the lead pellet so that we can continue with the calculation.