Question

A 2,000 kg freight train is traveling on the railroad tracks from Birmingham to Mobile. Its traveling at a speed of 25 m/sec. What is the kinetic energy of the train?
Captionless Image
625,000 J
490,000 J
50,000 J
25,000 J

Answer 1

The kinetic energy (KE) of an object can be calculated using the formula:

\[
KE = \frac{1}{2}mv^2
\]

where:
- \( m \) is the mass of the object (in kilograms),
- \( v \) is the speed of the object (in meters per second).

For the freight train:
- \( m = 2000 \) kg
- \( v = 25 \) m/s

Plugging in the values:

\[
KE = \frac{1}{2} \times 2000 \, \text{kg} \times (25 \, \text{m/s})^2
\]

Calculating \( (25 \, \text{m/s})^2 \):

\[
(25 \, \text{m/s})^2 = 625 \, \text{m}^2/\text{s}^2
\]

Now substitute that back into the KE equation:

\[
KE = \frac{1}{2} \times 2000 \, \text{kg} \times 625 \, \text{m}^2/\text{s}^2
\]

\[
KE = 1000 \times 625
\]

\[
KE = 625,000 \, \text{J}
\]

Therefore, the kinetic energy of the train is **625,000 J**.