Question

Тело массой 0,3кг падает с высоты 5м, найдите скорость и кинетическую энергию тела в момент удара об землю

Answer 1

По закону сохранения энергии
m*g*h = m*V^2/2
2*g*h=V^2
V= √2*g*h=√2*10*5=10 м/с

Answer 2

Problem Analysis

We are given the mass of an object (0.3 kg) and the height from which it falls (5 m). We need to find the velocity and kinetic energy of the object at the moment it hits the ground.

Solution

To solve this problem, we can use the principles of conservation of energy. The potential energy of the object at the initial height is equal to the kinetic energy of the object at the moment it hits the ground.

Calculation

The potential energy (PE) of an object is given by the formula: PE = m * g * h, where m is the mass of the object, g is the acceleration due to gravity (approximately 9.8 m/s^2), and h is the height.

Given: - Mass (m) = 0.3 kg - Height (h) = 5 m

Using the formula for potential energy, we can calculate the potential energy (PE) of the object at the initial height: PE = m * g * h

Substituting the given values: PE = 0.3 kg * 9.8 m/s^2 * 5 m

Now, we can calculate the velocity (v) of the object at the moment it hits the ground using the formula for kinetic energy (KE): KE = (1/2) * m * v^2

Since the potential energy at the initial height is equal to the kinetic energy at the moment of impact, we can equate the two equations: PE = KE

Substituting the values for potential energy and mass: m * g * h = (1/2) * m * v^2

Simplifying the equation: v^2 = 2 * g * h

Taking the square root of both sides: v = sqrt(2 * g * h)

Substituting the values for acceleration due to gravity and height: v = sqrt(2 * 9.8 m/s^2 * 5 m)

Now we can calculate the velocity (v) of the object at the moment it hits the ground.

Finally, we can calculate the kinetic energy (KE) of the object at the moment of impact using the formula: KE = (1/2) * m * v^2

Substituting the values for mass and velocity: KE = (1/2) * 0.3 kg * (v^2)

Now we can calculate the kinetic energy (KE) of the object at the moment it hits the ground.

Calculation Results

Using the given values, we can calculate the velocity and kinetic energy of the object at the moment it hits the ground.

The velocity (v) of the object at the moment it hits the ground is approximately 9.9 m/s.

The kinetic energy (KE) of the object at the moment it hits the ground is approximately 1.47 J.

Answer

The velocity of the object at the moment it hits the ground is approximately 9.9 m/s, and the kinetic energy of the object at that moment is approximately 1.47 J.