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 520 kilograms. How much kinetic energy do they have?



(1 point)
Responses

458,640 J
458,640 J

451,584.0 J
451,584.0 J

90,480.6 J
90,480.6 J

91,894.4 J

1 answer

To calculate the kinetic energy (KE) of the horse and jockey, we can use the formula:

\[ KE = \frac{1}{2} m v^2 \]

where:

  • \( m \) is the mass (in kilograms),
  • \( v \) is the velocity (in meters per second).

Given the mass \( m = 520 \) kg and the velocity \( v = 18.8 \) m/s, we can plug these values into the formula:

\[ KE = \frac{1}{2} \times 520 , \text{kg} \times (18.8 , \text{m/s})^2 \]

Calculating \( (18.8 , \text{m/s})^2 \):

\[ (18.8)^2 = 353.44 , \text{m}^2/\text{s}^2 \]

Now substitute this back into the kinetic energy formula:

\[ KE = \frac{1}{2} \times 520 , \text{kg} \times 353.44 , \text{m}^2/\text{s}^2 \]

Now calculate \( \frac{1}{2} \times 520 = 260 \):

\[ KE = 260 , \text{kg} \times 353.44 , \text{m}^2/\text{s}^2 \]

Calculating the final multiplication:

\[ KE = 92,894.4 , \text{J} \]

Thus, the kinetic energy of the horse and jockey is approximately:

\[ \boxed{91,894.4 , \text{J}} \]