What is the velocity of an object dropped from a height of 300 m?

[Dustobusto]

Homework Statement

What is the velocity of an object dropped from a height of 300 m when it hits the ground?

Homework Equations

s(t) = s₀ +v₀t -1/2gt²

v(t) = v₀ - gt

s₀ = initial height

v₀ = initial velocity

v(t) = s'(t)

The Attempt at a Solution

Attempted this for a while, can't seem to get it right. I know initial height = s₀ = 300m.

g, as given by the book = 9.8 (represents gravity)

I understand that when trying to find maximum height, velocity = zero. For this, I assume maximum velocity is found when s(t) = zero. Should I believe that when s₀ = 300, v₀ and t = zero?

 

[EngnrMatt]

Remember that g is -9.81 m/s². That is, it is a negative value.
try this equation:


v² = v₀² + 2g(x-x₀)

 

[Dustobusto]

I appreciate you giving me a new equation, but I'm trying to solve this within the context of the information given. I doubt I'm supposed to solve using that equation. No offense intended.

 

[nil1996]

From the given eqn.s
you can use s(t) = s₀ +v₀t -1/2gt²
put s₀ =0;v₀t=0;g=9.8m/s²;s(t)=300m

from this you will get time(t) required for the body to reach the ground.

now take the equation

v(t) = v₀ - gt

put v₀ =0;g=9.8m/s²
also put the time(t) found from the previous eqn.

v(t) is the required velocity.

 

[Dustobusto]

Dammit. Thanks nil. Dammit dammit..I was so close. I just had a few things wrong here and there..

But yeah, I had the right idea, was so close. Oh well.