# Kinematic problem: velocity and stuff

• selssk
In summary, the stone will reach the ground in 2 seconds. It will be traveling at 12 m/s when it hits the ground.
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 ^^

selssk said:
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
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In future, please fill in the template, don't delete it.

haruspex said:
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.

selssk said:
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.

Delta2
PhysicS FAN said:
which means that this is not free fall
It is free fall. It is not free fall from rest.

SammyS and hmmm27
selssk said:
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 ^^
$${v_f}^2={v_i}^2+2aΔx$$

## What is kinematics?

Kinematics is the branch of physics that deals with the study of motion of objects without considering the forces that cause the motion.

## What is velocity?

Velocity is the rate of change of an object's position with respect to time. It is a vector quantity that includes both magnitude and direction.

## How is velocity different from speed?

Velocity and speed are often used interchangeably, but they are not the same. While speed only considers the magnitude of an object's motion, velocity takes into account the direction of motion as well.

## What is the equation for average velocity?

The equation for average velocity is v = (xf - xi) / t, where v is the average velocity, xf is the final position, xi is the initial position, and t is the time interval.

## How do I solve kinematic problems involving velocity?

To solve kinematic problems involving velocity, you can use the equations of motion, such as v = u + at and s = ut + 1/2at^2, where v is final velocity, u is initial velocity, a is acceleration, t is time, and s is the displacement of the object.

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