Question

электровоз массой 100 т при торможении движется равнозамедленно и уменьшает свою скорость с 54км/ч до 3м/с.Какая работа была совершена при этом силами трения?Ответ представьте в мегаджоулях

Answer 1

Работа = масса/2(разность квадратов скоростей)
A=100000 кг/2*(225-9)=10800000 Дж=1080кДж= 1,1МДж

Answer 2

Calculation of Work Done by Friction

To calculate the work done by friction, we need to determine the force of friction and the distance over which it acts. Given the mass of the electric locomotive as 100 tons (or 100,000 kg), the initial speed as 54 km/h, and the final speed as 3 m/s, we can calculate the work done by friction.

First, let's convert the initial speed from km/h to m/s: - Initial speed = 54 km/h = 15 m/s.

Next, we can calculate the deceleration (negative acceleration) of the electric locomotive: - Deceleration = (final speed - initial speed) / time - Assuming the time taken to decelerate is not provided, we'll assume it to be 10 seconds for this calculation. - Deceleration = (3 m/s - 15 m/s) / 10 s = -1.2 m/s^2.

The force of friction can be calculated using Newton's second law of motion: - Force of friction = mass * acceleration - Force of friction = 100,000 kg * (-1.2 m/s^2) = -120,000 N.

Since the locomotive is moving in the opposite direction of the force of friction, the work done by friction is negative. The work done by friction can be calculated using the formula: - Work done by friction = force of friction * distance - Distance is not provided in the question, so we'll assume it to be 100 meters for this calculation. - Work done by friction = -120,000 N * 100 m = -12,000,000 J or -12 MJ (megajoules).

Therefore, the work done by the force of friction during the deceleration of the electric locomotive is approximately -12 megajoules.