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The equation is given by v = 10(1 - 2.718^[-t/(2.5)] )

 

Here's a graph of the function.......https://www.desmos.com/calculator/qgavq5phwq

 

 

(a) You should be able to handle the table part just by plugging in values 0, .5, 1, 1.5 .....4 for t

 

(b) This is already done, above....

 

(c).....I can see  that the tangent line to the graph when t = 2 is going to intercept the t  axis at a point where t < 0.  It will be easier to answer (d) first......and then come back and draw this tangent line and the enclosing triangle........

 

(d)  The derivative of the function can be found as follows :

v  =  10(1 - 2.718^[-t/(2.5)] )   =  10 - 10(2.718)^(-.4t )

dv / dt   = -10 ( -.4)ln(2.718)*(2.718)^(-.4t))

And evaluating this at t = 2 gives us a slope of about 1.797

 

And.....when t = 2, v = about 5.506

Now to find out where the tangent line intercepts the t axis, we can solve this equation.....

(5.506 - 0) / (2 - t)  = 1.797

5.506 / 1/797  = 2 - t

t = 2 - 5.506/1/797 = about - 1.064

 

So....to draw the enclosing triangle  ....  draw a segment from (-1.064, 0) to (2,0).....then draw another segment from (2, 0) to (2, 5.506)....then draw a final segment from (2, 5.506) back to (-1.064, 0)And, of course the slope of the tangent at t = 2 = 1.797 = dv /dt at this point = the change in V/sec when t = 2

 

Lastly.....the equation of the tangent line can be found by:

v - 0 = 1.797(t - (-1.064))

v = 1.797t + 1.912

 

And here's the graph of the function and the tangent line to the graph when t = 2

 

 

 

May 17, 2015
May 16, 2015

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