(III) (a) Calculate the impulse experienced when a 55-kg person lands on firm ground after jumping from a height of 2.8 m. (b) Estimate the average force exerted on the person's feet by the ground if the landing is stiff-legged, and again (c) with bent legs. With stiff legs, assume the body moves 1.0 cm during impact, and when the legs are bent, about 50 cm. [Hint: The average net force on him, which is related to impulse, is the vector sum of gravity and the force exerted by the ground. See Fig. 7-34.] We will see in Chapter 9 that the force in (b) exceeds the ultimate strength of bone (Table 9–2). mg F. grd FIGURE 7-34 Problem 24.

A bowling ball hangs from a 1.0-m-long cord, Fig. 7–30: (i) A 200-gram putty ball moving 5.0 m/s hits the bowling ball and sticks to it, causing the bowling ball to swing up; (ii) a 200-gram rubber ball moving 5.0 m/s hits the bowling ball and bounces straight back at nearly 5.0 m/s, causing the bowling ball to swing up. Describe what happens. (a) The bowling ball swings up by the same amount in both (i) and (ii). (b) The ball swings up farther in (i) than in (ii). (c) The ball swings up farther in (ii) than in (i). (d) Not enough information is given; we need the contact time between the rubber ball and the bowling ball. (i) (ii)

a)Calculate the impulse experienced when a 75 kg person lands on firm ground after jumping from a height of 3.0 m. b)Estimate the average force exerted on the person's feet by the ground if the landing is stiff-legged. With stiff legs, assume the body moves 1.1 cm during impact. [Hint: The average net force on her which is related to impulse, is the vector sum of gravity and the force exerted by the ground.] c)Estimate the average force exerted on the person's feet by the ground if the landing is with bent legs. When the legs are bent, assume the body moves about 41 cm during impact.