Answer :
Final answer:
The 45 kg runner moving at 7 m/s has greater kinetic energy (1575.5 joules) compared to the 93 kg runner moving at 3 m/s (418.5 joules), as calculated by the kinetic energy formula, KE = ½ mv2.
Explanation:
To determine which runner has greater kinetic energy, we need to use the kinetic energy formula: KE = ½ mv2, where m is the mass in kilograms and v is the speed in meters per second.
For the 45 kg runner moving at 7 m/s, the kinetic energy is:
KE = ½ × 45 kg × (7 m/s)2
= ½ × 45 kg × 49 m2/s2
= 1,575.5 joules
For the 93 kg runner moving at 3 m/s, the kinetic energy is:
KE = ½ × 93 kg × (3 m/s)2
= ½ × 93 kg × 9 m2/s2
= 418.5 joules
Comparing these two values, the 45 kg runner has the greater kinetic energy.
Kinetic Energy = (1/2) (mass) (speed)
First runner: KE = (1/2) (45kg) (49 m/s) = 1,102.5 Joules
Second runner: KE = (1/2) (93kg) (9 m/s) = 418.5 Joules
The first runner has 163% more kinetic energy than the second runner has.
