(II) A 2.0-kg purse is dropped from the top of the Leaning Tower of Pisa and falls 55 m before reaching the ground with a speed of 27m/s. What was the average force of air resistance?

Suppose a 65-kg person jumps from a height of 3.0 m down to the ground. Estimate the decelerating force if the person lands stiff-legged so d ≈ 1.0 cm.

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(II) The drag force on large objects such as cars, planes, and sky divers moving through air is more nearly F_D = -cv². For this quadratic dependence on v, determine a formula for the terminal velocity v_T, of a vertically falling object..

(III) An object moving vertically has ${\overrightarrow{v}}_{}={\overrightarrow{v}}_0$ at t = 0. Determine a formula for its velocity as a function of time assuming a resistive force F = -bv as well as gravity for two cases: ${\overrightarrow{v}}_0$ is upward.

Air resistance acting on a falling body can be taken into account by the approximate relation for the acceleration: a = dv/dt = g ― kv, where k is a constant. Determine an expression for the terminal velocity, which is the maximum value the velocity reaches.

(II) The terminal velocity of a 3 x 10^-5 kg raindrop is about 9 m/s. Assuming a drag force F_D = -bv, determine the time required for such a drop, starting from rest, to reach 63% of terminal velocity.