Understanding Train Traction Forces

What is traction in the context of trains?

• The speed at which a train travels

• The actual force a train uses to push itself forward on the track

• The resistance a train faces from the wind

• The weight of the train

Answer explanation

Traction refers to the actual force a train uses to push itself forward on the track. It is essential for movement and overcoming resistance, unlike speed, weight, or wind resistance, which are related but distinct concepts.

To move forward while running, what must you do?

• Jump as high as possible

• Exert force with your feet onto the street

• Move your arms quickly

• Lean backwards

Answer explanation

To move forward while running, you need to exert force with your feet onto the ground. This force propels you forward, making it the essential action for running effectively.

What determines the amount of traction available to a train?

• The colour of the train

• The amount of motive power available

• The number of passengers

• The length of the track

Answer explanation

The amount of motive power available directly affects a train's ability to generate traction. More power allows for better acceleration and the ability to overcome resistance, making it the key factor in determining traction.

Why does a heavy train require more traction than a light rail vehicle?

• Because it is longer

• Because it needs more force to move

• Because it has more wheels

• Because it travels faster

Answer explanation

A heavy train requires more traction because it has greater mass, which means it needs more force to overcome inertia and start moving. This is why the correct answer is 'Because it needs more force to move'.

Which type of locomotive disposes more power?

• Light rail vehicle

• Heavy rail locomotive

• Passenger car

• Tram

Answer explanation

Heavy rail locomotives are designed for high power output, enabling them to haul large loads over long distances. In contrast, light rail vehicles, trams, and passenger cars are generally less powerful, focusing on efficiency and passenger comfort.

What else, besides traction, is governed by the available power of a train?

• The number of carriages

• The maximal velocity the train can attain

• The colour of the train

• The number of stops

Answer explanation

The available power of a train not only affects traction but also determines the maximal velocity it can achieve. More power allows for higher speeds, making this the correct choice. The other options are not directly influenced by power.

What does the traction curve show?

• The number of passengers at each station

• The available traction at each velocity

• The length of the train over time

• The temperature of the engine

Answer explanation

The traction curve illustrates the available traction at each velocity, indicating how much pulling force a train can exert at different speeds. This is crucial for understanding performance and efficiency.

If you run in a crosswind or uphill, what do you need more of?

• Shoes

• Motive power

• Water

• Rest

Answer explanation

Running in a crosswind or uphill requires more effort and energy, which is referred to as 'motive power'. This is essential to overcome the additional resistance and maintain speed.

What is the extra amount of force needed to overcome obstacles like wind or hills called?

• Traction force

• Resistance force

• Gravitational force

• Frictional force

Answer explanation

The extra amount of force needed to overcome obstacles like wind or hills is called resistance force. This force opposes motion and must be overcome to maintain movement.

For a train, what does the resistive force depend on?

• The colour of the train

• The velocity of the train

• The number of wheels

• The type of track

Answer explanation

The resistive force on a train primarily depends on its velocity. As the speed increases, the air resistance and friction forces also increase, affecting the overall resistive force experienced by the train.