Question

Решите подробно пожалуйста 3.Поезд массой 200 тонн при торможении уменьшает свою скорость с 54 до 18 км\час за 50 сек. Найти силу трения колес во время торможения. ПОЖАЛУЙСТА ПОМОГИТЕ!

Answer 1

Problem Analysis

We are given the following information: - Mass of the train: 200 tons - Initial speed: 54 km/h - Final speed: 18 km/h - Time taken to reduce speed: 50 seconds

We need to find the force of friction acting on the wheels during braking.

Solution

To find the force of friction, we can use the equation:

Force of friction = (mass of the train) x (change in velocity) / (time taken)

Let's calculate the force of friction step by step.

1. Convert the mass of the train from tons to kilograms: - 1 ton = 1000 kg - Mass of the train = 200 tons x 1000 kg/ton = 200,000 kg

2. Convert the initial and final speeds from km/h to m/s: - 1 km/h = 1000 m/3600 s - Initial speed = 54 km/h x 1000 m/3600 s = 15 m/s - Final speed = 18 km/h x 1000 m/3600 s = 5 m/s

3. Calculate the change in velocity: - Change in velocity = Final speed - Initial speed = 5 m/s - 15 m/s = -10 m/s (negative sign indicates a decrease in speed)

4. Calculate the force of friction: - Force of friction = (mass of the train) x (change in velocity) / (time taken) - Force of friction = 200,000 kg x (-10 m/s) / 50 s

Now, let's calculate the force of friction.

Calculation

Mass of the train: 200,000 kg

Change in velocity: -10 m/s

Time taken: 50 s

Force of friction: (200,000 kg x (-10 m/s)) / 50 s = -40,000 N

Answer

The force of friction acting on the wheels during braking is -40,000 N. The negative sign indicates that the force of friction is acting in the opposite direction to the motion of the train.

Please note that the negative sign indicates the direction of the force, and it does not affect the magnitude of the force.