Instantaneous velocity of a object in projectile motion

[NightRunnerz]

Homework Statement

stone is thrown horizontally with a initial speed of 8.0 m/s (Vxi)
Air resistance is negligible. average acceleration due to gravity = 9.8 N/Kg (down) [ay]

Homework Equations

dx= Vxi/ time
Vfy= vyi + ay x time
Instantaneou velocity equation? :S

The Attempt at a Solution

okay so it tells me to find horizontal and vertical components of displacement and instantaneous velocity at time=0.0s/1.0s/2.0s and 3.0s isn't Vyi given (initial y velocity SINCE it's 0?) and (vxi is also give - 8.0 m/s)
BUt how do i find INSTANTANEOUS velocity?

 

[tiny-tim]

Welcome to PF!

Hi NightRunnerz! Welcome to PF!

… how do i find INSTANTANEOUS velocity?

Instantaneous velocity just means the velocity at that particular moment (ie, the word "instantaneous" is unnecessary )

(and if you need the speed, use Pythagoras! )

 

[NightRunnerz]

OKAY so by velocity you mean V as in speed right?
dotdotdot m/s2?
...m/s2?

 

[tiny-tim]

Hi NightRunnerz!

(just got up :zzz: …)

okay so it tells me to find horizontal and vertical components of displacement and instantaneous velocity at time …

OKAY so by velocity you mean V as in speed right?

No, speed and velocity are different.

Speed is the magnitude of velocity.

Velocity has components, speed doesn't.

The question tells you to find the horizontal and vertical components of instantaneous velocity … that's v_x and v_y.

dotdotdot m/s2?
...m/s2?

m/s² is acceleration