Question

Не могу ребят решить! Помогите... Камень массой 0,4кг бросили вертикально вверх со скоростью 20 м/с. Чему равны кинетическая и потенциальная энергии камня на высоте 15 м/с

Answer 1

По формулам братец, по формулам.
Ek=mv^2\2 - кинетическая
Ep=mgh - потенциальная

Ek= 0.4*20^2\2= 88
Ep=0, так как тело движется вверх, а потенциальная расчитывается только при равновесии или стоячем состоянии

Answer 2

Problem Analysis

We are given the mass of a stone (0.4 kg) and its initial velocity (20 m/s) when thrown vertically upwards. We need to find the kinetic and potential energy of the stone at a height of 15 m.

Solution

To solve this problem, we can use the conservation of mechanical energy. At any point during the stone's motion, the sum of its kinetic and potential energy remains constant.

Let's calculate the kinetic energy and potential energy of the stone at a height of 15 m.

Calculating Kinetic Energy

The kinetic energy of an object is given by the formula:

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

Substituting the given values: - Mass of the stone = 0.4 kg - Velocity of the stone = 15 m/s (at a height of 15 m)

Kinetic Energy = (1/2) * 0.4 kg * (15 m/s)^2

Calculating the kinetic energy using the above formula, we get:

Kinetic Energy = 0.4 kg * 112.5 m^2/s^2

Simplifying the expression, we find:

Kinetic Energy = 45 J

Therefore, the kinetic energy of the stone at a height of 15 m is 45 Joules.

Calculating Potential Energy

The potential energy of an object at a certain height is given by the formula:

Potential Energy = mass * gravity * height

Substituting the given values: - Mass of the stone = 0.4 kg - Height = 15 m

Potential Energy = 0.4 kg * 9.8 m/s^2 * 15 m

Calculating the potential energy using the above formula, we get:

Potential Energy = 58.8 J

Therefore, the potential energy of the stone at a height of 15 m is 58.8 Joules.

Summary

To summarize, the kinetic energy of the stone at a height of 15 m is 45 Joules, and the potential energy is 58.8 Joules.

Please let me know if you need any further assistance.