Archive for December 17th, 2009
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I live in central Jersey and last Friday around 8:30 PM I heard what sounded like a very loud explosion in the distance. Well I tried to find out what happened that night, but no luck. Nothing on the news, nothing in the newspaper the next day. In todays paper, a state police spokesman said the explosion was caused by (and I quote) "the harsh blastoff of a NASA rocket that lifted off from Wallops Island, Va." Now there is 220 miles between where I was and Wallops Isl. Va. It seems to me that an explosion heard TWO STATES away would have produced a little news. If this "blastoff" was heard 220 miles to the north, then it was probably heard 220 miles to the south and 220 miles to the west and that covers a lot of area. Is there anyone out there who was near Wallops Island Va. last Friday around 8:30 and can you confirm or deny this "explosion". And if your not in the area of Wallops Island, did you hear the explosion and where were you?
The story specifically states "at about 8:27 PM Friday"
That’s odd. It couldn’t be possibly the "blastoff" within 220 miles. I’m sure you heard something else, but thank you for sharing about this with us. You might be lucky to hear this far, heh.
What formulas do i need to work this problem?
A toy rocket moving vertically upward passes by a 2.0 m high window whose still is 8.0 m above the ground. The rocket takes 0.15 s to travel the 2.0 m height of the window. What was the launch speed of the rocket, and how high will it go? Assume the propellant is burned very quickly at blastoff.
First, find the speed of the rocket when it reaches the bottom of the window sill :
Δy = v₀t + 0.5at²
v₀ = (Δy – 0.5at²) / t
= [2.0m - (0.5)(-9.8m/s²)(0.15s)²] / 0.15s
= 14m/s
Using the time kinematics equation, the inital speed from the ground may be found taking the speed already calculated as the final velocity :
v² = v₀² + 2aΔy
v₀² = v² – 2aΔy
= (14m/s)² – (2 x -9.8m/s² x 8.0m)
= 19m/s
Hope this helps!