Question

Which object has the greatest kinetic energy?(1 point) Responses a truck with a mass of 3,500 kg moving at 30 m/s a truck with a mass of 3,500 kg moving at 30 m/s a person with a mass of 73 kg running 6 m/s a person with a mass of 73 kg running 6 m/s a locomotive engine with a mass of 205,000 kg moving 5 m/s a locomotive engine with a mass of 205,000 kg moving 5 m/s a fast pitched baseball with a mass of .5 kg moving at 46.9 m/s

Answer 1

To find which object has the greatest kinetic energy, we can use the formula for kinetic energy (KE):

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

where \( m \) is the mass of the object and \( v \) is its velocity.

Let's calculate the kinetic energy for each object:

1. **Truck (3,500 kg, 30 m/s)**:
\[
KE = \frac{1}{2} \cdot 3500 \cdot (30)^2 = \frac{1}{2} \cdot 3500 \cdot 900 = 1,575,000 \text{ J}
\]

2. **Person (73 kg, 6 m/s)**:
\[
KE = \frac{1}{2} \cdot 73 \cdot (6)^2 = \frac{1}{2} \cdot 73 \cdot 36 = 1,314 \text{ J}
\]

3. **Locomotive engine (205,000 kg, 5 m/s)**:
\[
KE = \frac{1}{2} \cdot 205000 \cdot (5)^2 = \frac{1}{2} \cdot 205000 \cdot 25 = 2,562,500 \text{ J}
\]

4. **Fast pitched baseball (0.5 kg, 46.9 m/s)**:
\[
KE = \frac{1}{2} \cdot 0.5 \cdot (46.9)^2 = \frac{1}{2} \cdot 0.5 \cdot 2198.41 \approx 54.96 \text{ J}
\]

Now, let’s compare all the kinetic energies:

- Truck: 1,575,000 J
- Person: 1,314 J
- Locomotive: 2,562,500 J
- Baseball: 54.96 J

The object with the greatest kinetic energy is the **locomotive engine with a kinetic energy of 2,562,500 J**.