Question

A racehorse is running at 42 miles per hour, equivalent to 18.8 meters per second. The horse and its jockey have a combined mass of 512 kilograms. How much kinetic energy do they have?

KE = 12mv2
𝐾
𝐸

=

1
2
𝑚
𝑣
2

(1 point)
Responses

180,961.3 J
180,961.3 J

451,584.0 J
451,584.0 J

90,480.6 J
90,480.6 J

4,812.8 J

Answer 1

Compute KE = 1/2 m v^2.

v^2 = 18.8^2 = 353.44.
m v^2 = 512 × 353.44 = 180,961.28.
KE = 0.5 × 180,961.28 = 90,480.64 J ≈ 90,480.6 J.

Correct choice: 90,480.6 J.