## Sunday, May 4, 2014

### EJSS Projectile Motion Model for Primary School

EJSS Projectile Motion Model for Primary School

## Model

Projectile motion is a form of motion in which an object or particle (called a projectile) is thrown near the earth's surface, and it moves along a curved path under the action of gravity only. The only force of significance that acts on the object is gravity, which acts downward to cause a downward acceleration. There are no horizontal forces needed to maintain the horizontal motion – consistent with the concept of inertia.

## The equation that model the motion of the ball is:

$\frac{\delta x}{\delta t} = v_{x}$

$\frac{\delta v_{y}}{\delta t} = a_{x} = 0$

$\frac{\delta y}{\delta t} = v_{y}$

$\frac{\delta v_{y}}{\delta t} = a_{y} = -9.81$

## Energy Equations:

$Potential Energy = mgy$

where
$m$ is the mass of the object = 1 kg,
$g$ is the gravitational acceleration in y direction = $-9.81 \frac{m}{s^{2}}$
$y$ is the position in the upward direction

$Kinetic Energy = \frac{1}{2} mv^{2}$
where
$m$ is the mass of the object = 1 kg,
$v$ is the velocity of the object