Question 212724
A ball is thrown into the air its velocity is 45ft/s its height in feet after t sec is given by 45t-19t^2. Find the instantaneous velocity when t=2



Step 1.  Let height = h = {{{45t-19t^2}}}  where  velocity is 45 ft/s


Step 2.  Derivative of h = velocity = 45 - 36t.


Step 3.  Substitute t=2 into Step 2.  velocity = 45 -36(2)= 45 - 72 = -27 ft/s


Step 4.  Since velocity is negative it is heading down at 27 ft/s.


I hope the above steps were helpful. 

 
And good luck in your studies!


Respectfully,
Dr J


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