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Barefoot Friends
A teenager accidentally falls off a 10-meter-high platform diving board. His friend whips out his camera and takes a picture when the teenager is halfway to the water below to commemorate the embarrassing event and posts it on Facebook. How many seconds after the teenager fell off did his friend take the picture?
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Something is wrong, is it 1,020 or 1.020
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Aqui no Brasil não utilizamos tal notação; por isso, considere um erro de digitação. Se quiseres, podes comprovar analisando as respostas abaixo - Samuel e Pedro!
People in different countries have different notation for decimal places.
O que você fez com o 10 após o 5 = 10 + 0 + ...
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Ora, subtraí 5. Faça passo a passo e notará que economizei algumas linhas, talvez por essa razão não tenha percebido! Passe a variável para o lado esquerdo da igualdade e o termo independente para a direita...
t = g 2 h which h = 10/2 = 5 meters
H = (g.t^2)/2
5 = 4,9t^2 t = 1,01
To solve this problem, we use the equation d = d 0 + v t + 2 1 a t 2 . Note that in this particular problem, we have that v = 0 , a = 9 . 8 . We set d 0 = 0 for simplicity. We are trying to solve for the time t when the teenager has gone 5 meters. Thus the equation is 5 = 2 1 9 . 8 t 2 or t = 9 . 8 1 0 ≈ 1 . 0 1 0
teenafer felt half way that is s2-s1=10/2=5m s2-s1=ut+1/2at^2 u=0m/s a=g
solve 5=0+1/2 10 t^2 t^2=1 t=1s(negative value not possible)
Use II Eq. of Motion i.e. s=u t+1/2 g*t^{2} u=0 and s=5m(half way down) then after solving t=1.01 sec
Given, h=10 m (halfway height= 5 m) u=0 m/s (The boy was initially at rest) g=9.8 m/s ^2
we know, by the second equation of motion that, h=u t+1/2 at^2
put the values and you will get the correct answer. (Put h=5 m)
It is a girl apparently, not a boy.
Hello,y axis motion...
halfway down=5m,as initial velocity=0 m/s, so by applying v^2=u^2-2gs,substitute u=0 m/s and g= -9.8m/s/s, V^2=0^2-(2x-9.8x5)=98 therefore,v=(98)^0.5,use v=u-gt to find the time,so t=v-u/-g=(98)^0.5 - 0 / (-(-9.8))=~1.01s..
thanks...
Half of 10m = 5m, so : 5 = 10 + 0.t - 4.9.t.t => 0=5 - 4.9 t^2 => t^2 = 1.001 => t = 1.01s
5=0-0.5 9.8 t^2 solve it. you will get t=1
Using S=So +vot + at²/2:
5 = 10t²/2
t = 1s
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⎩ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎨ ⎪ ⎪ ⎪ ⎪ ⎪ ⎪ ⎧ α = − 9 . 8 m / s 2 V o = 0 m / s S o = 1 0 m S = 5 m t = S = S o + V o ⋅ t + 2 α ⋅ t 2 5 = 1 0 + 0 + 2 − 9 . 8 t 2 2 9 . 8 t 2 = 5 9 . 8 t 2 = 1 0 t 2 = 1 , 0 2 0 t = 1 . 0 1 s