Answer:
We need to find 5 + 10 + 15 + ... + 485 + 490 + 495. There are 99 numbers that are being added. To add this we can do 5 + 495, 10 + 490, 15 + 485 and so on. These pairs have a sum of 500 and since there are 98 / 2 = 49 pairs their sum is 500 * 49 = 24500. Since there is an odd number of numbers that are being added, there is one number that does not belong to a pair. That number is the 50th number in the list which is 50 * 5 = 250. Therefore the answer is 24500 + 250 = 24750.
Assuming this little game of catch took place on planet earth, negative acceleration due to gravity is -9.8 m/s .
Converting 30ft/s to m/s, initial velocity was 30ft/s x 0.305ft/meter = 9.14m/s
Let's find how long it took for the velocity to equal zero, meaning when the ball reached it's highest point and, for a split second, stopped in mid-air before falling back down.
V(t) = Vi + a*t , where V(t) is velocity as a function of time, a is acceleration due to gravity, and t is time. Set V(t) = 0
0 = 9.14 + (-9.8)* t Add -9.8t to both sides
9.8t = 9.14 Divide both sides by 9.8
t = 0.93 seconds
Let's say your hand is the base point, or where h=zero. We want to find how high above your hand the ball went before it started coming down. Using the distance, or in this case height, formula:
h = Vi*t + (1/2)at² Plug in Vi, a, and our t value, 0.93
h= 9.14 * 0.93 + (1/2)(9.8)(0.93²)
h= 8.5 + 4.9 (0.865)
h = 8.5+ 4.27
h = 12.74 meters
The ball made it 12.74 meters above your hand. Your friends had was one foot above yours, so let's subtract .305 meters to see how far it dropped from the peak height to his hand.
12.74-.305 = 12.43 meters
Let's use the distance formula again to see how long it took to come down. Remember that this time, initial velocity is zero, since the ball starts off suspended in the air.
-12.43 = 0*t + (1/2)(-9.8)(t²) Divide both sides by -9.8/2, or -4.9
2.5374 = t²
t = 1.59
The ball took .93 seconds to go up, and 1.59 seconds to come down to your friend's glove. The total time the ball was in the air:
.93 + 1.59 = 2.52 seconds
Rules to use
Rule 1: x^2 = x*x
Rule 2: (a+b)*(c+d) = a*(c+d)+b*(c+d)
Rule 3: a*(b+c) = a*b+a*c
Using those rules, we get the following
(6+u)^2 = (6+u)*(6+u) ... use rule 1
(6+u)^2 = 6*(6+u)+u*(6+u) ... use rule 2
(6+u)^2 = 6*6+6*u+u*6+u*u ... use rule 3
(6+u)^2 = 36+6u+6u+u^2 ... multiply
(6+u)^2 = u^2+12u+36 ... combine like terms and rearrange
Answer: u^2+12u+36
It takes about 1/186,282 seconds for light to travel 2000 meters
