Which has a greater kinetic energy a 20.0kg greyhound running at 16m/s or a 923.0kg polar bear running at 2.5m/s

Kinetic energy = (1/2) (mass) (speed)²

Dog:
KE = (1/2) (20 kg) (16 m/s)² = (10kg) (256 m²/s²) = 2,560 joules

Bear:
KE = (1/2) (923 kg) (2.5 m/s)² = (461.5kg) (6.25 m²/s²) = 2,884.4 joules

==> The bear has 12.7% more kinetic energy than the dog has.

He will also have more stored food energy than the dog,
especially after he catches and eats the dog.