Question

камень массой 5 кг упал с некоторой высоты. Найти кинетическую энергию камня через 2 с после падения.

Answer 1

Высота падения: H=(gt^2)/2=10*4/2=20 мПотенц.энергия: W=mgh=5*10*20=1000 Дж, которая при падении переходит в кинетическую. К середине пути потенциальная энергия упадет наполовину, т.е. станет равна 500 Дж. Кинетическая энергия станет равна 500 Дж

Answer 2

Calculation of Kinetic Energy

To calculate the kinetic energy of an object, we can use the formula:

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

Given that the mass of the stone is 5 kg, we need to find the velocity of the stone after 2 seconds of falling.

Finding the Velocity of the Stone

To find the velocity of the stone after 2 seconds of falling, we can use the equation of motion:

Velocity (v) = initial velocity (u) + acceleration (a) * time (t)

Since the stone is falling freely under the influence of gravity, the acceleration can be taken as the acceleration due to gravity, which is approximately 9.8 m/s^2.

Let's assume that the initial velocity of the stone is 0 m/s, as it is dropped from rest.

Using the equation of motion, we can calculate the velocity of the stone after 2 seconds:

v = u + a * t

v = 0 + 9.8 * 2

v = 19.6 m/s

Calculation of Kinetic Energy

Now that we have the velocity of the stone after 2 seconds, we can calculate its kinetic energy using the formula mentioned earlier:

KE = (1/2) * mass * velocity^2

KE = (1/2) * 5 * 19.6^2

KE ≈ 480.2 Joules

Therefore, the kinetic energy of the stone after 2 seconds of falling is approximately 480.2 Joules.

Please note that the above calculations assume no air resistance and a constant acceleration due to gravity.