Question

Человек массой 70 кг поднимается на Говерлу высотой 2000 м, а затем возвращается обратно. Какую работу совершает сила тяжести при подъеме? При спуске? За все время движения?

Answer 1

Только за подъем сила работа, совершенная силой тяжести, равна $A = mgh \approx 70*10*2000 = 1400000$ Дж. На обратный путь затрачивается такая же работа. А за все время движения при условии, что человек возвращается в начало отсчета, работа равна нулю.

Ответ: 1400000 Дж, 1400000 Дж, 0 Дж

Answer 2

Calculation of Work Done by Gravity

To calculate the work done by the force of gravity during the ascent and descent of a person on Mount Hoverla, we need to consider the change in height and the person's mass.

Given: - Mass of the person (m) = 70 kg - Height of Mount Hoverla (h) = 2000 m

Work Done during Ascent

During the ascent, the person is moving against the force of gravity. The work done by the force of gravity can be calculated using the formula:

Work = Force x Distance

In this case, the force is the weight of the person, which can be calculated using the formula:

Weight = Mass x Acceleration due to gravity

The acceleration due to gravity is approximately 9.8 m/s^2.

Therefore, the work done during the ascent can be calculated as follows:

Work = Weight x Distance

Work = (Mass x Acceleration due to gravity) x Distance

Work = (70 kg x 9.8 m/s^2) x 2000 m

Calculating this, we find that the work done by the force of gravity during the ascent is approximately 1,372,000 Joules.

Work Done during Descent

During the descent, the person is moving in the direction of the force of gravity. In this case, the work done by the force of gravity is negative because the force and displacement are in opposite directions.

The work done during the descent can be calculated using the same formula as before:

Work = Weight x Distance

Work = (Mass x Acceleration due to gravity) x Distance

Work = (70 kg x 9.8 m/s^2) x 2000 m

Calculating this, we find that the work done by the force of gravity during the descent is also approximately 1,372,000 Joules, but with a negative sign.

Total Work Done during the Entire Journey

To calculate the total work done by the force of gravity during the entire journey, we need to consider both the ascent and descent. Since the work done during the descent is negative, we can simply add the magnitudes of the work done during the ascent and descent:

Total Work = |Work during Ascent| + |Work during Descent|

Total Work = |1,372,000 Joules| + |-1,372,000 Joules|

Calculating this, we find that the total work done by the force of gravity during the entire journey is approximately 2,744,000 Joules.

Please note that this calculation assumes that the force of gravity remains constant throughout the journey and does not take into account other factors such as air resistance or changes in gravitational acceleration at different altitudes.