Question

Две задачи, пожалуйста. 1. Определите кинетическую и потенциальную энергию тела массой 200г, брошенного горизонтально с высоты 100м со скоростью 30км/ч, через 2с после бросания. 2. Лифт массой 1000кг поднимается лебёдкой с постоянным ускорением. Какая работа совершается при перемещении лифта на участке 1м, если этот участок лифт проходит со средней скоростью 5м/с, а модуль его скорости возрастает при этом на 0,5м/с? Трением пренебречь.

Answer 1

Task 1: Determining the kinetic and potential energy of a horizontally thrown object

To determine the kinetic and potential energy of an object, we need to consider the formulas for each type of energy.

Kinetic energy is given by the formula:

KE = (1/2) * m * v^2

where KE is the kinetic energy, m is the mass of the object, and v is the velocity of the object.

Potential energy is given by the formula:

PE = m * g * h

where PE is the potential energy, 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 of the object.

In this case, we have an object with a mass of 200 grams (0.2 kg) that is thrown horizontally from a height of 100 meters with a velocity of 30 km/h. We need to determine the kinetic and potential energy of the object after 2 seconds.

Let's calculate the kinetic energy first:

KE = (1/2) * m * v^2

Substituting the given values:

KE = (1/2) * 0.2 * (30 km/h)^2

To convert the velocity from km/h to m/s, we divide by 3.6:

KE = (1/2) * 0.2 * (30 km/h / 3.6)^2

Simplifying:

KE = (1/2) * 0.2 * (8.33 m/s)^2

KE = 0.2 * 34.7 J

KE = 6.94 J

The kinetic energy of the object after 2 seconds is approximately 6.94 Joules.

Next, let's calculate the potential energy:

PE = m * g * h

Substituting the given values:

PE = 0.2 * 9.8 m/s^2 * 100 m

PE = 19.6 J

The potential energy of the object after 2 seconds is approximately 19.6 Joules.

Therefore, the kinetic energy of the object is approximately 6.94 Joules and the potential energy is approximately 19.6 Joules after 2 seconds.

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