(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?

You are driving home in your 860-kg car at 15 m/s. At a point 45 m from the beginning of an intersection, you see a green traffic light change to yellow, which you expect will last 4.0 s, and the distance to the far side of the intersection is 65 m (Fig. 4–71). <IMAGE>

(a) If you choose to accelerate, your car's engine will furnish a forward force of 1200 N. Will you make it completely through the intersection before the light turns red?

Suppose a 65-kg person jumps from a height of 3.0 m down to the ground.

(c) 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 .

(a) For this quadratic dependence on v, determine a formula for the terminal velocity vτ , of a vertically falling object..

(III) 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. (

b) 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 (b) the time required for such a drop, starting from rest, to reach 63% of terminal velocity.

An 800-kg car is traveling along a horizontal road directly towards a cliff. The driver notices and brakes, resulting in a 5,000-N net force slowing the car down. If the car's initial speed was 20 m/s and the car stops just before going over the cliff, how far away was the car from the cliff when the driver hit the brakes?