A small ball made of Styrofoam packing material is dropped from a height of 3.0 m above the ground. Until it reaches terminal speed, the magnitude of its acceleration is given by a = g-bv. After falling through 1.0 m, the ball effectively reaches terminal speed and then takes 4.0 more seconds to reach the ground. The value of the constant b is (take g = 10 m/$s^2$)

• A

  $10s^{-1}$

• B

  $20 s^{-1}$

• C

  $5 s^{-1}$

• D

  $50 s^{-1}$