To determine which of the two (the dog or the boy) has lower kinetic energy, we can use the kinetic energy formula:
\[ KE = \frac{1}{2} mv^2 \]
where:
- \( KE \) is the kinetic energy,
- \( m \) is the mass,
- \( v \) is the velocity.
Since we do not have specific velocity values, we can discuss the kinetic energy qualitatively based on their masses and potential speeds.
- Mass of the dog: 63 kg
- Mass of the boy: 51 kg
Generally, the kinetic energy increases with both mass and velocity. If we assume both the dog and the boy are moving at the same speed, the dog would have a higher kinetic energy due to its larger mass (63 kg > 51 kg).
However, if their speeds differ, they could have varying kinetic energies regardless of mass. If the boy is running significantly faster than the dog, he could potentially have greater kinetic energy despite his lower mass.
To determine who has lower kinetic energy in a practical scenario, we would need the speeds of both the dog and the boy while they are running.
Thus, without specific velocities:
- If both are moving at the same speed: The boy has lower kinetic energy due to his lower mass.
- If the boy is moving much faster: He could have higher kinetic energy than the dog regardless of mass.
In conclusion, without velocity data, we cannot definitively answer who has lower kinetic energy. If we assume equal speeds, the boy would have the lower kinetic energy due to his smaller mass.