# Gravity and acceleration simple calculation

• forrestuv
In summary: If you want to double the distance at which the object will be at a certain time, you should increase the time of by 1.2 seconds.
forrestuv
With this formula for distance calculation with gravity acceleration:

distance = 1/2 × acceleration × time^2 + intial speed × time

what Initial Acceleration does an object need to touch the ground in 3secs from 7meters of heigth?
what's the formula for that?

thx

forrestuv said:
what Initial Acceleration does an object need to touch the ground in 3secs from 7meters of heigth?
I assume you want the initial speed, not acceleration. The acceleration of a falling body is fixed at 9.8 m/s^2.
what's the formula for that?
That formula will do. Just solve for the initial speed.

ops.. yes I need the initial speed..how to obtain that from the formula I posted?I'm a real noob in math :(

It's just a bit of algebra. Take a stab at it.

For a start, if you had A = B + C, how would you solve for C?

C=a-b ? :)

forrestuv said:
C=a-b ? :)
Exactly. So rearrange your formula accordingly.

distance = 1/2 × acceleration × time^2 + intial speed × time

ok so:

intial speed × time = distance - (1/2 × acceleration × time^2)

then:

initial speed = (distance - (1/2 × acceleration × time^2)) / time

is it right? :)

in my case:

h=7 mt
t=3 secs
g=9.8

initial speed = (distance - (1/2 × acceleration × time^2)) / time

initial speed= (h- (1/2 × g × t^2)) / t

(7-(0.5x9.8x9)) / 3

(7-44.1) / 3 = -12.3666

can you check if it is correct please ? :)

forrestuv said:
can you check if it is correct please ? :)
Yes, it's correct. The reason why it's negative is that you have to throw the object upwards for it to take that long to fall 7m. (If you just dropped it would take only 1.2 seconds to hit the floor.)

In your equation, you took down as positive.

thxxxxxx!
I appreciated your help very very much :)

Now I would like to obtain something impossible to calculate for me :)
I need to know the min Initial speed needed to have, at a certain time a distance greater than a number.

example:
if I throw a ball at an initial speed of 12 I want to be sure that at 2 secs the distance is greater than 8.
is it possible?

science fiction for me eheh :)

alternatively:

Giving a fixed Initial Speed, If I want to double the distance at which the object will be at a certain time, how much should I increase time of?

## What is gravity and how does it affect acceleration?

Gravity is a force that pulls objects towards each other. On Earth, gravity is what keeps our feet on the ground and causes objects to fall. It affects acceleration by constantly acting on objects, causing them to accelerate towards the Earth's surface at a rate of 9.8 meters per second squared.

## What is the difference between weight and mass?

Weight is the measure of the force of gravity acting on an object, while mass is the amount of matter an object contains. Weight can change depending on the strength of gravity, while mass remains constant.

## How can I calculate the acceleration of an object?

The acceleration of an object can be calculated by dividing the change in velocity by the time it takes for that change to occur. The equation for acceleration is a = (vf - vi) / t, where a is acceleration, vf is final velocity, vi is initial velocity, and t is time.

## Does the mass of an object affect its acceleration due to gravity?

Yes, the mass of an object does affect its acceleration due to gravity. The more massive an object is, the greater the force of gravity acting on it, and therefore the greater its acceleration towards the Earth's surface.

## Can gravity and acceleration be negative?

Yes, both gravity and acceleration can be negative. Negative acceleration, also known as deceleration, occurs when an object is slowing down. Negative gravity, also known as anti-gravity, is a theoretical concept that has not yet been proven to exist.

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