(II) Roger sees water balloons fall past his window. He notices that each balloon strikes the sidewalk 0.83 s after passing his window. Roger’s room is on the third floor, 15 m above the sidewalk. (a) How fast are the balloons traveling when they pass Roger’s window? (b) Assuming the  balloons are being released from rest, from what floor are they being released? Each floor of the dorm is 5.0 m high.

A typical male sprinter can maintain his maximum accelerationfor 2.0 s, and his maximum speed is 10 m/ s. After he reachesthis maximum speed, his acceleration becomes zero, and then he runs atconstant speed. Assume that his acceleration is constant during the first 2.0 s of the race, that he starts from rest, and that he runs in a straightline. What is the magnitude of his average velocity for a race of these lengths: (i) 50.0 m; (ii) 100.0 m; (iii) 200.0 m?

(III) An unmarked police car traveling a constant 95km/h is passed by a speeder traveling 135km/h Precisely 1.00 s after the speeder passes, the police officer steps on the accelerator; if the police car’s acceleration is 2.60m/s2 how much time passes before the police car overtakes thespeeder (assumed moving at constant speed)?

· (III) A falling stone takes 0.31 s to travel past a window 2.2 m tall (Fig. 2-41). From what height above the top of the window did the stone fall? To travel this - distance took 0.31s 2.2 m FIGURE 2-41 Problem 53.

6. (II) A particle at =-2.0s is at x 3.4 cm and at 12 = 4.5 s is at x2 = 8.5 cm. What is its average velocity? Can you calculate its average speed from these data? driving

14) If an object is thrown upward with an initial velocity of 80 ft/sec, its height after t sec is given byℎ(?) = 80? − 16?2   Find the maximum height attained by the object. (The object will attain maximumheight exactly at the halfway point in terms of the time t, where t = 0 is at the beginning of theobject's flight, and the final time is when the object hits the ground.)A) 64 ftB) 84 ftC) 80 ftD) 100 ft

A person driving her car at 35 km/h approaches an inter- section just as the traffic light turns yellow. She knows that the yellow light lasts only 2.0s before turning to red, and she is 28 m away from the near side of the intersection (Fig. 2–49). Should she try to stop, or should she speed up to cross the intersection before the light turns red? The intersection is 15 m wide. Her car's maximum deceleration is -5.8 m/s?, whereas it can accelerate from 45 km/h to 65 km/h in 6.0 s. Ignore the length of her car and her reaction time. – 28 m - -15 m→ FIGURE 2-49 Problem 73.

A person jumps out a fourth-story window 18.0m above a firefighter's safety net. The survivor stretches the net 1.0m before coming to rest Fig 2-45. (a) What average deceleration experienced by the survivor when she was slowed to rest by the net? (b) What would do to make it safer" (that is, to generate a smaller deceleration): would you stiffen or loosen the net? explain.

Can the velocity of an object be zero at the same instant its acceleration is non- zero? Elaborate.