course Phy 201
A ball is tossed upward at 15 meters / second from a height of 12 meters above the ground. Assume a uniform downward acceleration of 10 m/s^2 (an approximation within 2% of the 9.8 m/s^2 acceleration of gravity).
How high does it rise and how long does it take to get to its highest point?
Since the intial velocity is at 15m/s and we know acceleration of -10m/s^2. Then after 1 second it will be at 5m/s. If we
travel another second then we would be a -5ms our downward fall. So with this we know at 1.5 seconds we are at the highest
point at 0m/s. So it takes 1.5 seconds to get to the highest point. Now to find the highest point we need to find vAve and *
by the change in time.15m/s/2=7.5m.7.5m*1.5s=11.25m. We add this onto the intial height of 12m and we get the highest point
of 23.25m
How fast is it then going when it hits the ground, and how long after the initial toss does it first strike the ground?
since we know the height is 23.25m and the acceleration is 10m/s^2 and intial velocity at the heigth of 23.25m is 0m/s.
We will use the equation y=y0+v0t+.5at^2 to find time.We will eliminate the y0 and v0 because they are equal to zero.
y=.5at^2. Flop this equation around again to find for time t^2=2y/a. Now take the sqrt of both sides
t=sqrt(2y/a).sqrt((2*23.25m)/10m/s^2)=sqrt(46.5m/10m/s^2)=sqrt4.65s=2.16seconds. Now we add this time to the intial 1.5
seconds we get a totla time of 3.66s.We now know time we can find v.v=v0+at.v=0+10m/s^2*2.16s=21.6m/s
At what clock time(s) will the speed of the ball be 5 meters / second?
As mentioned in the first question it will be at 1 second
At what clock time(s) will the ball be 20 meters above the ground?
We will use the equation y=y0+v0t+.5at^2. Since y0 and v0 is 0 we will eliminate these.We get y=.5at^2. Flop it again
t^2=2y/a.sqrt of both sides t=sqrt(2y/a).Y=3.25 being this is the difference between 20m and 23.25.
t=sqrt((2*3.25)/10m/s^2).t=sqrt(6.5/10m/s^2).t=sqrt.65s.t=.81seconds
How high will it be at the end of the sixth second?
answer/question/discussion:
below the earths surface somewhere. It will have already hit the ground by then
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