Though slow on land, the leatherback turtle holds the record for the fastest water speed of any reptile: 9.78

m/s. It is also among the largest of reptiles. Suppose the largest leatherback yet discovered were to swim
at the top leatherback speed. If its kinetic energy was 6.08 × 104 J, what was its mass?

1 answer

To find the mass of the leatherback turtle, we can use the formula for kinetic energy (KE):

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

Where:

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

Given:

  • \( KE = 6.08 \times 10^4 , J \)
  • \( v = 9.78 , m/s \)

We can rearrange the formula to solve for mass \( m \):

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

Now substituting in the known values:

\[ m = \frac{2 \cdot 6.08 \times 10^4 , J}{(9.78 , m/s)^2} \]

Calculating the denominator:

\[ (9.78 , m/s)^2 = 95.4884 , m^2/s^2 \]

Now substituting this back into the mass formula:

\[ m = \frac{2 \cdot 6.08 \times 10^4 , J}{95.4884 , m^2/s^2} \]

Calculating the numerator:

\[ 2 \cdot 6.08 \times 10^4 , J = 1.216 \times 10^5 , J \]

Now dividing:

\[ m = \frac{1.216 \times 10^5 , J}{95.4884 , m^2/s^2} \approx 1270.12 , kg \]

Thus, the mass of the leatherback turtle is approximately:

\[ \boxed{1270.12 , kg} \]