+0  
 
+2
69
2
avatar+270 

https://vle.mathswatch.co.uk/images/questions/question16491.png 

 

 

smileysmileysmiley

qualitystreet  Feb 13, 2018
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2+0 Answers

 #1
avatar+85673 
+3

We have  that

 

d  = kt^2       and we need to find  k

 

We know that

 

80  = k (4)^2

80  =  16k    divide both sides by 16

5  = k

 

So......we want to know this distance

 

[Distance it falls  in  (4 + 8) =  12 sec ]   -  [ Distance it falls in 4 sec ]  =

 

5(12)^2  -  5(4)^2  =

 

5  (12^2  - 4^2 )  =

 

5 (144 - 16)   =

 

5 (128)   =   

 

640 m  in the next 8 sec 

 

 

cool cool cool

CPhill  Feb 13, 2018
 #2
avatar+270 
+1

Thanks for your help.

 

smileysmileysmiley

qualitystreet  Feb 14, 2018

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