# Speed and Velocity question

1. Aug 5, 2013

### MathHelpa

This is a horizontal projectile problem off a building.

Is the speed of an object equal to:

$v=a*t$
or
$v = |v|$ (magnitude)

Current problem:
$Velocity = √(v_0^2 + g^2(2h/g)) positive below x axis$

$t = √(2h/g)$

so is the speed suppose to be $v = g√(2h/g) m/s$

or is it suppose to be

$|v| = √(v_o^2 + g^2(2h/g)) m/s$

2. Aug 5, 2013

### Staff: Mentor

v=at is true only if the acceleration is constant and the initial velocity is zero, it is not true in your case. You can use it for one velocity component (but not the full velocity) here.

v and |v| are different objects (vector and scalar), you cannot compare them with an equal sign.

The "m/s" there does not make sense. The units are in g and h.

Please post the full problem statement, if you have questions how to interpret it.

3. Aug 5, 2013

### micromass

Staff Emeritus