# Vectors and Projectiles - Mission VP8 Detailed Help A 3-kg projectile is launched upward and rightward from ground level. The magnitude of the acceleration of the 3-kg projectile at the peak of its trajectory is ... Definition of a Projectile: A projectile is an object for which the only force acting upon it is gravity. The force of air resistance is negligibly small or nonexistent for a projectile. The acceleration of any object can be calculated from knowledge of its mass and the forces acting upon it. For a projectile, the only force acting upon it is gravity; its value can be calculated from the object's mass (see Formula Frenzy section). Once the net force is known, the acceleration can be calculated using Newton's second law equation (see Formula Frenzy section). The calculated acceleration value should not be a surprising result. The relationship between net force (Fnet), mass (m) and acceleration (a) is expressed by the equation   a = Fnet/ m The force of gravity (Fgrav) which acts upon an object is mathematically related to the mass of an object (m) by the equation:   Fgrav= mass • g   where g is the acceleration caused by gravity alone. The value of g on Earth is 9.8 m/s/s (approximately 10 m/s/s).  