Vf vertical velocity Monday, October 19, 2015

Monday, 10/19 Unit 3: Two dimensional motion Respond to the following on your warm-up sheet In the game modern warfare, you fire your M203 grenade horizontally from the roof of a building that is 11 meters tall. The grenade lands 114 meters from the base of your building. What is the initial horizontal velocity of your grenade? Upcoming dates Friday, 10/23 – quiz Thursday, 10/29 – projectile motion project due Thursday, 10/29 – unit 3 test See my webpage for additional 2NW dates

Monday, 10/19 Unit 3: Two dimensional motion Respond to the following on your warm-up sheet In the game modern warfare, you fire your M203 grenade horizontally from the roof of a building that is 11 meters tall. The grenade lands 114 meters from the base of your building. What is the initial horizontal velocity of your grenade?

Horizontal Projectile What we know A projectile has two dimensions to it’s motion. Horizontal Vertical The initial velocity (Vi) in the horizontal is a value that is given to us or we can calculate it. The initial velocity (Vi) in the vertical is always zero.

Horizontal Projectile What about Final Velocity? Watch animation http://www.physicsclassroom.com/mmedia/qt/vectors/prehlp.cfm

Horizontal Projectile – Velocity Horizontal Velocity There is no force acting on the object horizontally therefore inertia applies and the horizontal velocity remains constant. There is no change in velocity therefore there is no acceleration. What do you think the final horizontal velocity would be just before it hits the ground?

Horizontal Projectile – Velocity Vertical Velocity When the projectile is launched there is no initial vertical velocity. After the projectile is launched the force of gravity starts to have an affect on the vertical motion of the object. The objects starts to accelerate (velocity is changing). The velocity starts to increase. What do you think the final vertical velocity of an object would be just before it hits the ground?

Calculating final horizontal final velocity Horizontal Velocity Vertical Velocity ∆x = 9.2 ∆y = 11.47 m Vi = 6 m/s Vi = 0 m/s a = 0 m/s a = 9.8 m/s t = 1.53 s U: Vf E: Vf = Vi + at S: Vf = (6) + (0)(1.53) S: Vf = 6 m/s

Calculating final vertical final velocity Horizontal Velocity Vertical Velocity ∆x = 9.2 ∆y = 11.47 m Vi = 6 m/s Vi = 0 m/s a = 0 m/s a = 9.8 m/s t = 1.53 s U: Vf E: Vf = Vi + at S: Vf = (0) + (9.8)(1.53) S: Vf = 14.99 m/s

Practice with your elbow partner