General Physics Please explain thoroughly. Thank you! 3) Lois and Clark live in
ID: 1283496 • Letter: G
Question
General Physics
Please explain thoroughly. Thank you!
3) Lois and Clark live in a high-rise apartment building. Lois lives on the 30th floor, and Clark lives on the 32nd floor directly above her. When Clark was visiting Lois, he left his cell phone in her apartment. When she finds it, she calls him up and tells him she'll toss it up to him through the window. She throws the cell phone straight up to him with an initial speed of 20.0 m/s. But being the klutz that he is, Clark misses catching the phone both on its way up, and again as it is falling down. Meanwhile, Jesse is walking along on the ground below when he sees what's going on. When he sees Clark miss catching the phone for the second time on its way down, he instantly starts running to see if he can catch the phone before it hits the ground. a) If Jesse is a distance d = 25.0 m away at the instant Clark misses the phone for the second time as it's falling, how fast must Jesse run to just catch the phone before it hits the ground? b) Jesse, too busy running as fast as he can, didn't notice that when the phone passed Lois on its way down, she tried to reach out the window and catch it. Unfortunately, she reached too far and fell out the window. Clark notices Lois fall out the window and is horrified. It takes him 1.70 s to change into his Superman uniform and jump out the window to try to save Lois. Assuming he jumps out the window with zero velocity and then accelerates with a constant downward acceleration, what must Superman's minimum acceleration be if he has to get to the ground before Lois, in time to catch her? c) After Jesse catches the phone, he continues running for a bit with the same constant velocity he had before. Meanwhile, Superman is concerned that he'll crash into Jesse when he lands on the ground. Where will Jesse be when Superman hits the ground? 3) a.______ b.______ c.________ Figure 3 - (a) Lois throws Clark's cell phone up to him. Jesse is a distance, d, away when Clark misses catching it. (b) After Lois falls out the window, Superman dives down to save her. (Not to scale.)Explanation / Answer
intial speed of phone when it is thrown = 20 m/s
speed of phone when it misses clark for second time U = ?(202 - 2*g*5.5 ) = 17.1 m/s
now time taken by phone to reach ground be t
90.5 = Ut + 0.5gt2
4.9t2 + 17.1t - 90.5 = 0
t = 2.9 sec
speed of jesse = distance covered by jesse /time = 25/2.9 = 8.6 m/s
2)
when lois falls time taken by her to reach ground t = ?(2h/g) = 4.1 sec
since superman starts after 1.7 sec he should reach ground before 2.4 sec
so min accleration = 2h/t2 = 2*90.5/2.42 = 31.4 m/s2
3)
distance of jesse and superman = speed*time difference = 8.6*(4.1-2.9) = 10.32 m after crossing the building
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