Question

A ball falls from a tall bridge. The ball has a mass of 0.15 kg. The air density is 1.225 kg/m3
. The ball’s surface area is 0.0026 m2
. The ball’s coefficient of drag is 0.007. What is the ball’s terminal velocity?(1 point)
Responses

30.4 m/s
30.4 m/s

164 m/s
164 m/s

363 m/s
363 m/s

402 m/s

1 answer

To find the terminal velocity of a falling ball, we can use the following formula for terminal velocity \(v_t\):

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

where:

  • \(m\) = mass of the object (kg)
  • \(g\) = acceleration due to gravity (\(9.81 , m/s^2\))
  • \(\rho\) = air density (\(kg/m^3\))
  • \(C_d\) = coefficient of drag
  • \(A\) = surface area of the object (\(m^2\))

Now, substituting the values provided:

  • \(m = 0.15 , kg\)
  • \(g = 9.81 , m/s^2\)
  • \(\rho = 1.225 , kg/m^3\)
  • \(C_d = 0.007\)
  • \(A = 0.0026 , m^2\)

Plugging in the values:

\[ v_t = \sqrt{\frac{2 \times 0.15 \times 9.81}{1.225 \times 0.007 \times 0.0026}} \]

Calculating the numerator:

\[ 2 \times 0.15 \times 9.81 = 2.943 \]

Calculating the denominator:

\[ 1.225 \times 0.007 \times 0.0026 \approx 0.000022573 \]

Now calculating \(v_t\):

\[ v_t = \sqrt{\frac{2.943}{0.000022573}} \approx \sqrt{130175.8678} \approx 360.5 , m/s \]

Rounding gives us approximately \(363 , m/s\).

Thus, the terminal velocity is \(\boxed{363 , m/s}\).