Question

Камень брошен вертикально вверх. На пути 1 м его кинетическая энергия уменьшилась на 16 Дж. Какую работу совершила сила тяжести на этом пути? В ответе будет 16 или -16?

Answer 1

Calculation of Work Done by Gravity

To calculate the work done by the force of gravity on the stone, we need to determine the change in its kinetic energy. Given that the stone is thrown vertically upwards and its kinetic energy decreases by 16 J over a distance of 1 m, we can use the work-energy principle to find the work done by gravity.

According to the work-energy principle, the work done on an object is equal to the change in its kinetic energy. In this case, the work done by gravity is equal to the change in the stone's kinetic energy.

Let's assume the initial kinetic energy of the stone is K1 and the final kinetic energy is K2. The change in kinetic energy is given by:

ΔK = K2 - K1

Since the stone is thrown vertically upwards, its initial velocity is positive and its final velocity is zero at the highest point of its trajectory. Therefore, the initial kinetic energy is greater than the final kinetic energy.

Now, let's calculate the work done by gravity using the change in kinetic energy:

Work done by gravity = -ΔK

The negative sign indicates that the work done by gravity is in the opposite direction of the displacement of the stone.

Based on the given information, the change in kinetic energy is 16 J. Therefore, the work done by gravity is:

Work done by gravity = -16 J

So, the answer is -16 J.