1. What is the acceleration due to gravity? 2. Use your kinematics equations to solve the following problem: The observation deck of tall skyscraper 370 m above the street. Determine the time required for a penny to free fall from the deck to the street below. *Bonus! What will you be doing tonight?

12/2/10

 the branch of classical mechanics or mechanical engineering that describes the motion of bodies (objects) and systems

 Projectile – an object shot through the air  Trajectory – an object’s path through space

 The trajectory of a projectile is a parabola

If one object is dropped and one object is thrown horizontally from the same height, which one will land first? Support your prediction! Write and share with your elbow partner!   ectors/hlp.cfm ectors/hlp.cfm

 Gravity ONLY AFFECTS THE Y-COMPONENT!!!! Time Horizontal Velocity Vertical Velocity 0 s 20 m/s, right 0 1 s 20 m/s, right 9.8 m/s, down 2 s 20 m/s, right 19.6 m/s, down 3 s 20 m/s, right 29.4 m/s, down 4 s 20 m/s, right 39.2 m/s, down 5 s 20 m/s, right 49.0 m/s, down

 Your fave equations in one dimension!

 Horizontally launched – (viy = 0 m/s)  Angled – ( viy > 0 m/s)

 A bullet fired horizontally at m/s hits the ground in 2.0 seconds. Calculate the vertical & horizontal displacements.

 A bullet fired horizontally at m/s hits the ground in 2.0 seconds. Calculate the vertical & horizontal velocities just before it hits the ground.

In the x direction  a x = 0  v ix = v fx = v x  d x = v x t  v x =v i cosθ In the y direction: a y = -9.8m/s 2 =g d y =v iy t+ ½ gt 2 v iy =v i sinθ v fy =v f sinθ v fy =v iy +gt v fy 2 =v iy 2 +2gd d y = (v fy +V iy )t/2

 What is a projectile?  What is a trajectory?  What is the trajectory of a projectile?

In the x direction  a x = 0  v ix = v fx = v x  d x = v x t In the y direction: a y = -9.8m/s 2 =g V iy = 0 m/s d y = ½ a y t 2 v fy =gt v fy 2 =2g d y d y = (v fy )t/2

 Use the rest of class to work on your homework. Don’t forget to sign up on the group presentation sheet!

 A bullet fired horizontally at 600 m/s hits the ground in 3 seconds. Calculate the vertical & horizontal displacements.

 Use the rest of class to finish your homework. If you are finished with your homework, check over it, then work on your project. I will be coming around to meet with each group individually.

A matchbox car rolls horizontally off the edge of a table seconds later it lands 1.0 meters from the base of the table.  How high is the table?  How fast was it going when it left the edge of the table?  What is its speed and angle at impact? v=? d y =? d x =1.0 m

 Use the following formula to solve the problem: v fy 2 =v iy 2 +2ad  A ball is launched straight up in the air. It reaches a maximum height of 0.6 m. What is its launch (initial) velocity?

 A bullet fired horizontally at 600 m/s hits the ground in 3 seconds. Calculate the vertical & horizontal velocities just before it hits the ground.

 What are the important variables that are always true for horizontally launched projectiles?

 Horizontally Launched  Angled

 v ix =v fx  V iy =0  a x =0  a y =-9.8

 How could we modify these variables for angled kinematics problems? Write your response in your notes, then share with your elbow partner.

 v iy =v i sinθ  v x =v i cosθ  a x =0  a y =-9.8

1. Traveling up: 1. v iy =v i sinθ i 2. v x =v i cosθ i 3. v fy =0 (at max height) 2. Traveling down: 1. v fy =v f sinθ f 2. v x =v ix 3. v iy =0 (at max height)

 A golf ball is struck giving it an initial velocity of 250 m/s at 30 o from horizontal. Calculate: 1. The initial vertical velocity. 2. The initial horizontal velocity. 3. The maximum height of the ball in its flight. 4. The time the ball remains in the air. 5. The horizontal displacement of the ball in its flight.

 A projectile is launched at 35 m/s at an angle of 56 o above horizontal on a level field.  What is the speed and direction of the projectile at its highest point?  What is the range of the projectile (horizontal distance to its landing point)

 Work on homework  If finished, submit and work quietly on something else.

 Graphs (Position-Time; Velocity-Time)

 If the projectile lands at the same height it started from, θ i

 A golf ball is struck giving it an initial velocity of 200 m/s at 60 o from horizontal. Calculate: 1. The initial vertical velocity. 2. The initial horizontal velocity. 3. The time the ball remains in the air.