When a 65 kg skydiver jumps from a plane, her speed steadily increases until air resistance provides a force that balances the force due to free fall. How fast is the skydiver falling if her kinetic energy at the moment is 7.04 x 10^5 J?

1 answer

To determine the speed of the skydiver, we can use the formula for kinetic energy, which is given by:

\[ KE = \frac{1}{2} mv^2 \]

where:

  • \( KE \) is the kinetic energy,
  • \( m \) is the mass of the skydiver,
  • \( v \) is the velocity.

Given:

  • \( KE = 7.04 \times 10^5 , J \)
  • \( m = 65 , kg \)

We can rearrange the kinetic energy formula to solve for \( v \):

\[ v = \sqrt{\frac{2 \times KE}{m}} \]

Substituting the values we have:

\[ v = \sqrt{\frac{2 \times 7.04 \times 10^5 , J}{65 , kg}} \]

Calculating the numerator:

\[ 2 \times 7.04 \times 10^5 , J = 1.408 \times 10^6 , J \]

Now, calculate the whole expression:

\[ v = \sqrt{\frac{1.408 \times 10^6 , J}{65 , kg}} \approx \sqrt{21678.46 , \text{m}^2/\text{s}^2} \]

Finally, taking the square root:

\[ v \approx 147.12 , \text{m/s} \]

Thus, the speed of the skydiver is approximately \( 147.12 , \text{m/s} \).