Term
T or F. When a projectile is fired at an angle from the ground (neglecting air resistance) the horizontal and vertical velocity components are both zero at the highest point in its flight. 

Definition
False. At the highest point in the projectile flight, only the vertical velocity reaches zero. Horizontal velocity is not zero as long as the projectile is fired at some angle other than 90 degrees. 


Term
A projectile is fired from ground level at an angle, with an initial vertical speed of 30 m/s and initial horizontal speed of 15 m/s. Assuming the ground is level, air resistance is negligible, and g = 10 m/s^2, the distance horizontally that the object will strike from the initial point is ____________. 

Definition
90 m. Vertical time to top is 3 seconds Total time in the air is 6 seconds Horizontal distance: d = vt d = 15 m/s x 6 seconds = 90 m. 


Term
For a freely falling object in projectile motion, what is the acceleration in the xdirection? 

Definition
Zero. Gravitational acceleration has only a downward, constant yaxis component with a magnitude of g. 


Term
What is the acceleration in the ydirection for a freely falling body in projectile motion? 

Definition
The acceleration is a = g, where g is 9.81 m/s^2. The equations of motion are the same as for other systems of constant acceleration. 

