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If a ball is dropped, how long must it fall to attain a velocity of 12.55m/s?

Guest Mar 22, 2015

Best Answer 

 #3
avatar+92777 
+10

I shall show you the calculus solution

 

$$\\\ddot{y}=9.8\\\\
\dot{y}=9.8t+c\\\\
when \;\;t=0\;\;\dot{y}=0\;\;so\;\;c=0\\\\
\dot{y}=9.8t\\\\
$Find t when $\;\dot{y}=12.55\\\\
12.55=9.8t\\\\
t=\frac{12.55}{9.8}=1.28sec$$

 

There you go - that was pretty simple too.  :)

Melody  Mar 23, 2015
 #1
avatar+92777 
+10

did you need to use physics formula or calculus?

 

 

If a ball is dropped, how long must it fall to attain a velocity of 12.55m/s?

I will assume that you are on Earth near seal level      gravity=9.8m/s^2

a=9.8,   u=0,   v=12.55,   t=?

v=u+at

12.55=0+9.8*t

12.55=9.8t

 

$${\frac{{\mathtt{12.55}}}{{\mathtt{9.8}}}} = {\frac{{\mathtt{251}}}{{\mathtt{196}}}} = {\mathtt{1.280\: \!612\: \!244\: \!897\: \!959\: \!2}}$$

 

1.28 seconds

 

If you need to use calc you can ask and it shall be done.

Melody  Mar 23, 2015
 #2
avatar+87301 
+5

That linear formula looks pretty straight forward to me, Melody......

Is it more confusing with calculus???

 

   

CPhill  Mar 23, 2015
 #3
avatar+92777 
+10
Best Answer

I shall show you the calculus solution

 

$$\\\ddot{y}=9.8\\\\
\dot{y}=9.8t+c\\\\
when \;\;t=0\;\;\dot{y}=0\;\;so\;\;c=0\\\\
\dot{y}=9.8t\\\\
$Find t when $\;\dot{y}=12.55\\\\
12.55=9.8t\\\\
t=\frac{12.55}{9.8}=1.28sec$$

 

There you go - that was pretty simple too.  :)

Melody  Mar 23, 2015
 #4
avatar+87301 
0

Yep...equally easy......

 

  

CPhill  Mar 23, 2015

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