# 2 objects 1 up and 1 down thrown

1. Feb 4, 2005

### runner1738

An object is thrown downward with an initial speed of 9 m/s from a height of 40 m above the ground. At the same instant, a second object is propelled vertically from ground level with a speed of 14 m.s. The acceleration of gravity is 9.8 m/s^2. At what height above the ground will the two objects pass each other? Abswer in units of m?

2. Feb 4, 2005

### christinono

Same idea as this one. Equal the distances.

3. Feb 4, 2005

### runner1738

i guess i just cant do math in general casue i got 9t + 1/2(9.8)t^2=14t+1/2(-9.8)t^2
9.8t^2-5t=0 , that i got .5102040816 * what though?

4. Feb 4, 2005

### christinono

Remember, the one being thrown down has a NEGATIVE velocity (negative direction).

5. Feb 4, 2005

### runner1738

ok gotcha i think, thanks for all the help

6. Feb 4, 2005

### runner1738

ok this time around i got 2.346938976 from -9t+1/2(9.8)t^2=14t+1/2(-9.8)t^2, but the answer is supposed to be in m? and i have time

7. Feb 5, 2005

### christinono

From the time, you can find the distance. Just use the formula:

$$d=V_it + \frac{1}{2}at^2$$