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physics help please help!!!!?
Physics help please??!?
A student drops a book out of a window in a tall building. If it took 1.51 seconds for the book to hit the ground, how high above the ground is the window? meters
What is the books maximum speed during flight? m/s
At what time does this occur? seconds
How high above the ground is the book when it is falling at a speed of 393cm/s? m
3 Answers
- 8 years ago
hight: gravity is generaly an acceleration of 9.81m/s^2. therefore the distance is s=ut+0.5at^2 metres
distance = 0.5 x 9.81 x 1.51^2
distance = 11.18 metres
Max speed : v=u+at , where V is final velocity, which is the fastest.
v=0 + (9.81 x 1.51) = 14.81 m/s
this occours after 1.51 seconds, as the greatest speed is gotten before it hits the ground.
im not bothered answering the last q, its a bit of an effort, sorry :)
- ?Lv 78 years ago
How about U doing the math on this one:
h = 1/2gt² {where t = 1.51 s, g = 9.81 m/s²}
Vf = √2gh {where h = answer above}
t = √2h/g {where h = answer above}
when book is falling at a V = 3.93 m/s:
V = √2gH
H = V²/2g {where V = 3.93 m/s}
- Anonymous8 years ago
x=Vit+1/2at^2
x=1/2g(1.51^2)
x=(4.9)(2.28)
x= 11.2 m off the ground. (ANSWER)
Maximum speed is Vf, so
Vf=Vi+at
Vf=(9.8)(1.51)
Vf=14.8 m/s (ANSWER)
This occurs at 1.51 s because it was right before impact.
393 cm/s = 3.93 m/s
V^2=2aX
X=Vf^2/2a
X=3.93^2/(2*9.8)
X=0.79 m (ANSWER)