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Object falling down and object falling up

  • #1

Homework Statement


A object A falling down at terminal velocity of 20 m/s, at 1000m above the ground another object B fly at it at an initial velocity of 125 m/s.

a) how much time before object A hits object B?


Homework Equations



X = Xo + Vo(t) + 1/2AT^2

G = 9.8 m/s^2

The Attempt at a Solution



using the equation i found it takes object A 12.385 second to fall down from 1000
m while object B 6.321 second to reach 1000 m

but im not sure how i can find out when they will hit each other.
 

Answers and Replies

  • #2
rl.bhat
Homework Helper
4,433
5
Suppose they meet at a height x from the ground. Then the distance moved by A is 1000 - x and distance move by B is x. A is moving with uniform velocity where as B is moving with the acceleration. When they meet, they must have taken the same time. So write two equations and solve for x.
 
  • #3
SammyS
Staff Emeritus
Science Advisor
Homework Helper
Gold Member
11,237
962
Does an object falling at terminal velocity accelerate? Why not?

So, you time for object A is incorrect.

Object B will not reach a height of 1000 m.

An object launched downward at 125 m/s from a 1000 m altitude, will reach the ground in 6.396 s, ignoring air resistance.
 
Last edited:

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