Question

Which object has the greatest kinetic energy? (1 point)
• a green car with a mass of 500kg
moving at 21 m/s
O a blue car with a mass of 500 kg moving at 30 m/s
a red car mass of 500 kg moving at 3 m/s
O a yellow car with a mass of 500 kg
moving at 12 m/s

Answer 1

Answer

Answer 2

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.

Since all cars have the same mass (500 kg), we just need to compare their velocities to find the one with the greatest kinetic energy. We can calculate the kinetic energy for each car:

1. **Green car**:
\[
KE = \frac{1}{2} (500) (21^2) = 0.5 \cdot 500 \cdot 441 = 110250 \, \text{J}
\]

2. **Blue car**:
\[
KE = \frac{1}{2} (500) (30^2) = 0.5 \cdot 500 \cdot 900 = 225000 \, \text{J}
\]

3. **Red car**:
\[
KE = \frac{1}{2} (500) (3^2) = 0.5 \cdot 500 \cdot 9 = 2250 \, \text{J}
\]

4. **Yellow car**:
\[
KE = \frac{1}{2} (500) (12^2) = 0.5 \cdot 500 \cdot 144 = 36000 \, \text{J}
\]

Now, comparing the kinetic energies:

- Green car: 110250 J
- Blue car: 225000 J
- Red car: 2250 J
- Yellow car: 36000 J

The blue car has the greatest kinetic energy at **225000 J**.

Answer 3

The blue car with a mass of 500 kg moving at 30 m/s has the greatest kinetic energy.