# Comparing Speed and Kinetic Energy in a Railroad Car Collision

• mitchmcsscm94
In summary, the conversation discusses test corrections and three different problems involving mass, velocity, and kinetic energy. The first problem involves a railroad car colliding with and connecting to another car, with the question of how the speed and kinetic energy of the connected cars compare to the single car before the collision. The second problem involves a ball with mass and momentum, and determining which choice represents its kinetic energy. The third problem involves a new planet with twice the mass and radius of Earth, and determining the gravitational force a person weighing 500N on Earth would experience on its surface.
mitchmcsscm94
Test corrections!

## Homework Statement

1.) a railroad car of mass m is moving with speed v when it collides with and connects to a second railroad car of mass 3m, initially at rest. how do the speed and kinetic energy of the connected cars compare to those of the single car of mass m before the collision.
speed/Kinetic Energy
a.)less,less​
b.)less,the same​
c.) the same, less​
d.) greater, the same​

2.) a ball of mass m and momentum p has kinetic energy equal to which of the following?
a.) 1 p2/2 m​
b.) p2/m​
c.)2 (p2/m)​
d.)1m/2p2

3.) a new planet is discovered that is twice the Earth's mass and twice the Earths radius. On the surface of this new planet, a person who weights 500N on Earth would experience a gravitational force of
a.)125N​
b.)250N​
c.)500N​
d.)1000N​

## The Attempt at a Solution

1 is not b
2 is not b
3 is not c

What have you tried?

Where are you stuck?

Can you give any reasons as to why the listed answers are wrong?

A hint for #2: What is the formula for p? Pk\lug that formula in for p in the four choices. See if any of them result in the formula for kinetic energy.

## 1. How does speed affect kinetic energy in a railroad car collision?

Speed directly affects kinetic energy in a railroad car collision. The greater the speed of the train, the greater the kinetic energy it possesses. This means that a train traveling at a higher speed will have a greater impact and cause more damage in a collision compared to a train traveling at a slower speed.

## 2. Is kinetic energy the only factor that determines the severity of a railroad car collision?

No, there are other factors that can also contribute to the severity of a railroad car collision. The mass and size of the train, as well as the materials and structure of the train cars, can also play a role in the impact and damage caused in a collision.

## 3. How is kinetic energy calculated in a railroad car collision?

Kinetic energy is calculated using the formula: KE = 1/2 * m * v^2, where m is the mass of the train car and v is the velocity or speed of the train. This formula shows that the kinetic energy increases exponentially as the speed of the train increases.

## 4. Can the kinetic energy of a train be reduced in a collision?

Yes, the kinetic energy of a train can be reduced in a collision by decreasing its speed. This can be done through various safety measures such as braking systems, speed restrictions, and warning signals. By reducing the speed of the train, the amount of kinetic energy it possesses is also reduced, resulting in a less severe collision.

## 5. How can engineers and scientists use the concept of kinetic energy to improve railway safety?

Engineers and scientists can use the concept of kinetic energy to develop safety features and protocols for railways. By understanding how speed and kinetic energy affect the severity of collisions, they can design trains and infrastructure to minimize the impact and damage in case of a collision. They can also implement safety measures such as speed restrictions and warning systems to prevent collisions from occurring in the first place.

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