another hot-air balloon 10 meters above the ground is rising at a constant rate of 15 meters per second. To the nearest tenth of a second, after how many seconds will the 2 balloons be the same height above the ground? (I have the answer and it is 2.9 but I don't know how to get that answer) Please help!
2007-06-05 17:01:24 · 4 answers · asked by sarah b 1 in Science & Mathematics ➔ Physics
When the 2 balloons meet, their heights are equal.
Height of first balloon is 70 - 6t
Height of second balloon is 10 + 15t
(where t is time in seconds)
When they meet,
70 - 6t = 10 + 15t
subtract 10 from both sides
add 6t to both sides
60 = 21t
divide both sides by 21
2.9 = t
2007-06-05 17:09:03 · answer #1 · answered by maddog27271 6 · 1⤊ 0⤋
the first air balloon falls at a constant rate and the second ballon rises at a constant rate. We use x = vt for the motion of both balloons.
When they have the same height is when they meed
Because the second balloon is already at 10m, the distance between both balloon is only 60m
When both balloons travel toward each other, their distances will add to 60m.
distance of first balloon + distance of second balloon =60m
distance of first balloon = 6t
distance of second ballon = 15t
t is the time
6t + 15t = 60
25t = 70
t = 2.857s or round to 2.9s
2007-06-05 17:46:24 · answer #2 · answered by 7 · 0⤊ 0⤋
When the 2 balloons meet, their heights are equal.
Height of first balloon is 70 - 6t
Height of second balloon is 10 + 15t
(where t is time in seconds)
When they meet,
70 - 6t = 10 + 15t
subtract 10 from both sides
add 6t to both sides
60 = 21t
divide both sides by 21
2.9 = t
2007-06-05 17:42:01 · answer #3 · answered by rana_22_m 2 · 0⤊ 3⤋
They're 60 meters apart and the closing velocity between them is 21 m/s.
60/21 = 2.857 or about 2.9 seconds.
Doug
2007-06-05 17:46:40 · answer #4 · answered by doug_donaghue 7 · 0⤊ 0⤋