Another one that stumped me......please help
John was at the top of a ladder. He threw a ball straight up in the air with an initial speed of 10.0 m/s and the neighbours below heard it strike the ground 3.0 seconds later, how far above the ground was John when he threw the brush?
2007-03-07 10:06:46 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Physics
TankAnswe... got messed up with the Xs. He started out good.
s = 1/2gt^2 + v(0)t + s(0)
The result, s, will be the distance from the reference point. Let the reference point be the ground. And s(0) is the startting point, measured from ground. We can call it X. So X will be the height John through his whatever from.
s = (1/2)*(-9.8 m/s^2)*3^2 + 10 m/s*3 + X
s = -44.1 + 30 + X
s = -14.1 + X
X = 14.1 + s
OK, what's s? We know the ball (or whatever) ended up on the ground, the reference point. So s=0. And therefore
X = 14.1
2007-03-07 13:15:41 · answer #1 · answered by sojsail 7 · 0⤊ 0⤋
Well it all depends on how tall the ladder was when the bush fell out of his back pock as for as the ball is concerned. If John threw a ball up in the air with and intial speed of ten meters per second and the ball hit the ground 3.o seconds later the brush fell out of is pocket three feet..
2007-03-07 18:24:20 · answer #2 · answered by Tom Sawyer 6 · 0⤊ 0⤋
This is a multi-part equation.
You know that the ball had to decelerate (due to gravity) at 9.8 m/s^2 from 10 to zero, then it had to come back down. And you know t. And you can calculate time to decelerate to zero.
This gives you the time remaining (3.0s - t(decelerate)). And you know acceleration, and you can calculate final velocity. And that will allow you to calculate the height of john's arm when he released the brush/ball whatever.
2007-03-07 18:12:19 · answer #3 · answered by Brian L 7 · 0⤊ 0⤋
all ballistic motion =
s = 1/2gt^2 + v(0)t + s(0)
s = final position = -X (where X is how high John was)
t = 3 seconds
g = -9.8 m/s^2 (note downward direction)
v(0) = 10 m/s (upward = positive)
s(0) = initial position X
-X = 1/2(-9.8)(3)(3) + 10(3) + X
2X = 44.1 - 30
X = 7.05meters
2007-03-07 18:16:38 · answer #4 · answered by TankAnswer 4 · 0⤊ 0⤋
he didnt throw a brush. you said he threw a ball.
2007-03-07 18:10:16 · answer #5 · answered by Anonymous · 0⤊ 0⤋
too high to do math problems man
besides he threw a ball
2007-03-07 18:09:13 · answer #6 · answered by mobious_zero 2 · 0⤊ 0⤋
Brush??? what happened to the ball
2007-03-07 18:10:25 · answer #7 · answered by Anonymous · 0⤊ 0⤋
Hey Cosmo you didnt tell them how high i trew it but it was 23 ft i busted my a--- cpming off the ladderJohn
2007-03-07 18:12:50 · answer #8 · answered by havenjohnny 6 · 0⤊ 0⤋