Question #8c25d
3 Answers
Explanation:
Let's find the velocity
P.S. :- If you want to prove that too...
First we'll find
Now, the distance traveled from
Then we'll find the velocity
Kinematic expression is given as
#S=80t-16t^2#
Comparing it with the kinematic expression
#h=ut+1/2g t^2# , we see that
#u=80ftcdot s^-1# as given and#g=-32ftcdot s^-2# . Negative sign shows that gravity is acting against direction of initial motion.
When ball is
#v^2-u^2=2gs#
#=>v^2-80^2=2(-32)90#
#=>v^2=80^2+2(-32)90#
#=>v^2=6400-5760#
#=>v=+-25.3ftcdot s^-1# , rounded to one decimal place
Keeping in view the
Velocity of the ball on its way up
Velocity of the ball on its way down
Explanation:
There are two instances when the ball is 90 ft above the ground.
Applying the quadratic formula we get:
We know that:
To get the velocity at time t we take the 1st derivative:
After
The + sign means the velocity is vertical.
After
The - sign means the ball is falling to earth.