Names: __________________________ Date: _______________ Period: ____ Horizontal Projectiles Lab Activity – Online Simulation Open up the University of Colorado, PhET Projectile Motion simulation (http://phet.colorado.edu/new/index.php select Play with Sims>Physics>Projectile Motion>Run Now!) Spend a few minutes familiarizing yourself with the controls of the simulation before you begin the lab below. For projectiles launched horizontally, two relationships are valid: Height, dy = ½ gt2 and horizontal distance, dx = vt Part One: You will compare the time to the ground for several projectiles launched horizontally from the same height but at different velocities. Raise the red platform upon which the cannon sits to a height of your choice. KEEP IT AT THE SAME HEIGHT FOR EACH TRIAL. Rotate the cannon until it is horizontal. You can select an angle of zero in the box on the right. You may select any object to shoot out of the cannon. Now provide these velocities and fill in the chart below. To measure both height and horizontal distance, pull out tape from the tape measure. The height is measured from where the red platform touches the ground up to the “origin” that is inside the cannon. The horizontal distance is measured from that exact spot over to the location where the object lands. Make sure your tape measure line is perfectly vertical and perfectly horizontal. Height Velocity Horizontal distance Time to ground 30 m/s 20 m/s 10 m/s 0 m/s What do you conclude about the time required to reach the ground when horizontally launched at different velocities? Part Two: In this lab simulation, you will calculate the appropriate velocity required for a projectile to have a desired range when launched from a given height. The values for height, horizontal distance, and velocity will then be selected in the simulation and your predictions will be tested. Show all calculations. Height, dy = ½ gt2 and horizontal distance, dx = vt Height Horizontal Distance 5m 10 m 10 m 10 m 15 m 25 m 20 m 15 m Calculations use g = 9.8 m/s2 Required velocity Test your predictions: Using the tape measure, raise the platform to the different heights, measuring from the ground to the “origin” that is inside the cannon. Place the target at the horizontal distance, measuring from the center of the platform on the ground, not the edge of the platform. Now type in your calculated required velocity and test your prediction. Verify with your teacher that you have “hit the target”.