Physics Questions

[Shinigami345]

I'm taking a college level physics class, and I'm just a wee bit stuck on the following problems. It's an online course so I don't really have a teacher for it I could ask my High School's Science Teacher, but I don't have any classes with him and really don't want to have to show up before or after school to ask him. Classical Mechanics never really was my strong suit; I'm more of a Quantum kind of guy.


Question 1: Harry accidentally falls out of a helicopter that is traveling at 100 m/s. He plunges into a swimming pool 2 seconds later. Assuming no air resistance, what was the horizontal distance between Harry and the swimming pool when he fell from the helicopter?


Question 2: A boy on a 20 m tall tower throws a ball and 60 m horizontal from the base of the tower the ball lands on the ground. At what speed in m/s was the ball thrown?


Question 3:The movie "The Gods Must Be Crazy" begins with a pilot dropping a bottle out of an airplane. It is recovered by a surprised native below, who thinks it is a message from the gods. If The plane from which the bottle was dropped was flying at an altitude of 500m, and the bottle lands 400m horizontally from the initial dropping point, how fast was the plane flying when the bottle was released.

[xzid]

#1: 200m?

#2:

t^2 = 2y / g
t^2 = 2(20) / (9.8 s^2)
t^2 = 4.081s^2
t = 2.02s

took ~2 seconds to hit ground

60m / 2.02s = ~29.7m/s

#3: refer to #2

quantum physics without classical mechanics?

[FuyuKitsune]

1) 200m
He traveled 100m/s horizontal for 2 seconds.


2)  30m/s
We need horizontal speed in m/s. We have the meters, 60m, we just need time. We can get the time by figuring out how long it takes the ball to drop 20m.
The formulas are a pain to type so I used my dry-erase board. Here's a pic http://i55.tinypic.com/1zwnk34.jpg
v_i is the initial (vertical in this case) velocity, which is 0 because the ball was thrown vertically
The square root gets chopped off to retain precision because the least significant digit in the problem was *10^1 (the 20m and 60m)
Now just 60m / 2s = 30m/s

You're actually supposed to do significant figures only at the end of a problem but I forget and didn't want to take another picture.


3) Same deal as before but with different numbers. d=500m, which ends up making t=10.096375s
now 400m/10.096375s = 39.61817979m/s, use sigfigs to get 40m/s.

[_ANONYMOUS_]

I know the first 1 is 200m
 
The rest im not sure of but this might help you out
http://www.emu.edu.tr/mugp101/testque/SerwayTestQuestions.pdf

[FuyuKitsune]

lol, this thread is from 2 months ago. I think his work was due already

[_ANONYMOUS_]

lol oh yeah