Kinematic problem: velocity and stuff

[selssk]

1. A stone is thrown vertically downwards from the observation deck of the CN Tower, 400 m above the ground, with a velocity of 12 m/s [down].
A) How long will it take the stone to reach the ground ?
B) How fast will it be going when it hits the ground ?

I just got into physics, so I’m not that much familiar with the type of equation I should use. I’ve been trying to solve this problem for a while, so any help is appreciated ^^

 

[haruspex]

1. A stone is thrown vertically downwards from the observation deck of the CN Tower, 400 m above the ground, with a velocity of 12 m/s [down].
A) How long will it take the stone to reach the ground ?
B) How fast will it be going when it hits the ground ?

I just got into physics, so I’m not that much familiar with the type of equation I should use. I’ve been trying to solve this problem for a while, so any help is appreciated ^^

https://en.m.wikipedia.org/wiki/Equ...translational_acceleration_in_a_straight_line
To get further help you need to show some attempt, as per forum rules.
In future, please fill in the template, don't delete it.

 

[selssk]

https://en.m.wikipedia.org/wiki/Equ...translational_acceleration_in_a_straight_line
To get further help you need to show some attempt, as per forum rules.
In future, please fill in the template, don't delete it.

I can’t really add anything since I don’t know where to start, if I had done something, I would have added it, but I didn’t. As I said, I just got into physics so this is like my first questions.

 

[PhysicS FAN]

1. A stone is thrown vertically downwards from the observation deck of the CN Tower, 400 m above the ground, with a velocity of 12 m/s [down].
A) How long will it take the stone to reach the ground ?
B) How fast will it be going when it hits the ground ?

I just got into physics, so I’m not that much familiar with the type of equation I should use. I’ve been trying to solve this problem for a while, so any help is appreciated ^^

Well first of all the object is thrown with an initial velocity which means that this is not free fall. So there are two equations you need to use:
V=Vo + g*t and h= Vo*t + 1/2*g*t*t (where Vo is the initial velocity and g is the gravity acceleration which is constant g=10m/s*s) Now the known data are the height and the initial velocity so you need to combine the two equations and get the result.

 

[jbriggs444]

which means that this is not free fall

It is free fall. It is not free fall from rest.

 

[neilparker62]

1. A stone is thrown vertically downwards from the observation deck of the CN Tower, 400 m above the ground, with a velocity of 12 m/s [down].
A) How long will it take the stone to reach the ground ?
B) How fast will it be going when it hits the ground ?

I just got into physics, so I’m not that much familiar with the type of equation I should use. I’ve been trying to solve this problem for a while, so any help is appreciated ^^

$$ {v_f}^2={v_i}^2+2aΔx $$