Question
a balloon rises straight up to 5 ft/sec. and a crying child who lost the balloon is standing 40 ft away. how fast does the balloon move away from the child when it is 30 ft above the ground?
Answers
Steve
If the balloon is at height h, then the distance z from the child to the balloon is
z^2 = h^2 + 40^2
When h=30, z=50
So, now we want dz/dt when h=30
2z dz/dt = 2h dh/dt
Just plug in z=50 and h=30 and dh/dt=5 and solve for dz/dt
z^2 = h^2 + 40^2
When h=30, z=50
So, now we want dz/dt when h=30
2z dz/dt = 2h dh/dt
Just plug in z=50 and h=30 and dh/dt=5 and solve for dz/dt