Question

Мальчик на санках (их общая масса 50 кг) спустился с ледяной горы высотой 5м. Чему равна его скорость в конце спуска? Считать, что по склону горы санки скользили без трения.

Answer 1

Независимо от массы, скорость определяется из равенства кинетической энергии в конце спуска потенциальной энергии в его начале

$mgh = \frac{mv^{2}}{2} \\ v^{2} = 2gh\\ v = \sqrt{2gh} = \sqrt{2*9,8*5} = \sqrt{98} = 9,9$

Если принять g за 10, то, соответственно, √100 = 10

Answer 2

Calculation of the Boy's Speed at the End of the Descent

To calculate the boy's speed at the end of the descent, we can use the principle of conservation of energy. Since the sleds slide down the icy slope without friction, the only energy involved is potential energy and kinetic energy.

The potential energy at the top of the hill is given by the formula:

Potential Energy = mass * acceleration due to gravity * height

The kinetic energy at the bottom of the hill is given by the formula:

Kinetic Energy = 0.5 * mass * velocity^2

According to the principle of conservation of energy, the potential energy at the top of the hill is equal to the kinetic energy at the bottom of the hill. Therefore, we can equate the two equations:

mass * acceleration due to gravity * height = 0.5 * mass * velocity^2

We can simplify the equation by canceling out the mass:

acceleration due to gravity * height = 0.5 * velocity^2

Now we can solve for velocity:

velocity = sqrt(2 * acceleration due to gravity * height)

Substituting the given values:

velocity = sqrt(2 * 9.8 m/s^2 * 5 m)

Calculating the result:

velocity = sqrt(98 m^2/s^2) ≈ 9.90 m/s

Therefore, the boy's speed at the end of the descent is approximately 9.90 m/s.