# physics

posted by .

While standing on a bridge 30.0 m above the ground, you drop a stone from rest. When the stone has fallen 3.20 m, you throw a second stone straight down. What initial velocity must you give the second stone if they are both to reach the ground at the same instant? Take the downward direction to be the negative direction.

• physics -

d1 = 0.5g*t^2 = 30-3.2 = 26.8.
4.9t^2 = 26.8
t^2 = 5.47
t = 2.34 s. = Fall time of 1st stone.

The 2nd stone must fall 30 meters in
2.34 s.

d2 = Vo*t + 0.5g*t^2 = 30 m.
Vo*2.34 + 4.9(2.34)^2 = 30
2.34Vo + 26.83 = 30
2.34Vo = 30-26.83 = 3.17
Vo = 1.35 m/s. = Initial velocity of 2nd stone.

## Similar Questions

1. ### physics

While standing on a bridge 15.0 m above the ground, you drop a stone from rest. When the stone has fallen 3.10 m, you throw a second stone straight down. What initial velocity must you give the second stone if they are both to reach …
2. ### physics

While standing on a bridge 15.0 m above the ground, you drop a stone from rest. When the stone has fallen 3.10 m, you throw a second stone straight down. What initial velocity must you give the second stone if they are both to reach …
3. ### college physics

While standing on a bridge 15.0 m above the ground, you drop a stone from rest. When the stone has fallen 3.10 m, you throw a second stone straight down. What initial velocity must you give the second stone if they are both to reach …
4. ### physics

While standing on a bridge 15.0 m above the ground, you drop a stone from rest. When the stone has fallen 5.00 m, you throw a second stone straight down. What initial velocity must you give the second stone if they are both to reach …
5. ### physics

While standing on a bridge 18.5 m above the ground, you drop a stone from rest. When the stone has fallen 2.80 m, you throw a second stone straight down. What minimal initial velocity must you give the second stone if they are both …
6. ### physics

While standing on a bridge 45.0 m above ground, you drop a stone from rest. When the stone has fallen 3.80 m, you throw a second stone straight down. What initial velocity must you give the second stone if they are both to reach the …
7. ### Physics

While standing on a bridge 45.0 m above ground, you drop a stone from rest. When the stone has fallen 3.90 m, you throw a second stone straight down. What initial velocity must you give the second stone if they are both to reach the …
8. ### Physics

While standing on a bridge 45.0 m above ground, you drop a stone from rest. When the stone has fallen 3.90 m, you throw a second stone straight down. What initial velocity must you give the second stone if they are both to reach the …
9. ### Physics

While standing on a bridge 19.1 m above the ground, you drop a stone from rest. When the stone has fallen 3.40 m, you throw a second stone straight down. What minimal initial velocity must you give the second stone if they are both …
10. ### Physics

While standing on a bridge 18.3 m above the ground, you drop a stone from rest. When the stone has fallen 2.60 m, you throw a second stone straight down. What minimal initial velocity must you give the second stone if they are both …

More Similar Questions