If a ball is thrown into the air with a velocity of 30m/s, its height in metres after t seconds is given by y=30t-4.9t^2.
a) Find the average velocity for the time period beginning when t=2 and lasting 1 sec.
b) Find the instantaneous velocity when t=2.

Question

jhannybean · Answer

To find average velocity, use the second definition of the derivative. $$\frac{f(b)-f(a)}{b-a}$$

jhannybean · Answer

$$f(t) = 30t-4.9^2$$$$f(2)=~?$$$$f(1)=~?$$ Instantaneous velocity is found by taking the limit as $h\rightarrow 0$

zale101 · Answer

t=2 and lasting 1 sec
I was thinking
f(2)=?
f(2+1) which is f(3)=?

zale101 · Answer

And $ Average~ velocity=\Large\frac{f(3)-f(2)}{3-2}$

anonymous · Answer

How did you know to add the one?

zale101 · Answer

Because when it said t=2 and lasting 1 sec, there's time  after t=2 lasted a second later

jhannybean · Answer

Imagine the ball going up in 2 seconds, but coming down 3 seconds later.

jhannybean · Answer

factors such as wind resistance, gravitational pull, etc. You know, lots of minimal factors :P

anonymous · Answer

oohh i see thanks!