A ball falls from a tall bridge. The ball has a mass of 0.15 kg. The air density is 1.225 kg/m3

1.225 . The ball’s surface area is 0.0026 m2
0.0026 . The ball’s coefficient of drag is 0.007. What is the ball’s terminal velocity?
Responses

164 m/s

402 m/s

363 m/s

30.4 m/s

1 answer

To calculate the terminal velocity of the ball, we can use the formula for terminal velocity \( V_t \):

\[ V_t = \sqrt{\frac{2mg}{\rho C_d A}} \]

Where:

  • \( m \) is the mass of the object (0.15 kg),
  • \( g \) is the acceleration due to gravity (approximately \( 9.81 , \text{m/s}^2 \)),
  • \( \rho \) is the air density (1.225 kg/m³),
  • \( C_d \) is the drag coefficient (0.007),
  • \( A \) is the cross-sectional area (0.0026 m²).

Now, plug in the values:

  1. Calculate the numerator \( 2mg \):

\[ 2mg = 2 \cdot 0.15 , \text{kg} \cdot 9.81 , \text{m/s}^2 = 2.943 , \text{N} \]

  1. Calculate the denominator \( \rho C_d A \):

\[ \rho C_d A = 1.225 , \text{kg/m}^3 \cdot 0.007 \cdot 0.0026 , \text{m}^2 = 2.2357 \times 10^{-5} , \text{kg/m} \]

  1. Now, substitute these values back into the formula for \( V_t \):

\[ V_t = \sqrt{\frac{2.943}{2.2357 \times 10^{-5}}} = \sqrt{131526.06} \approx 363 , \text{m/s} \]

Thus, the terminal velocity of the ball is approximately 363 m/s.

The correct response is:

363 m/s