Post on 20-Jan-2016
Physics 10-29
Type 2 Projectile MotionType 3 Projectile Motion
Max HeightThrowing marshmellows
All late homework due Wednesday by Beginning of
homeroom!!!Nothing will be accepted after that
time
Some people need to take the last test
Physics tests are not yet graded
But I think all of the rest of the graded assignments are
All other grades will be added to the second marking period
Including the pictures of the 8 simple machines
(If you need an extra day to complete the assignment, take it)
Type 1
• What information is automatically given for a type 1 problem?
• Give an example of a type one projectile not connected to running a car off a cliff
Type one answers
• Both accelerations
• Vertical initial velocity = 0
• A person running off a dock
• A person shooting the gun horizontally
Type 2
• What is assumed to be given in a type 2 problem?
• Can you think of an example of a type 2 projectile not involving a soccer ball and a level playing field
Type 2 answers
• Both accelerations
• The vertical displacement = 0
• Kickoff at a football game
• A horse jumping over a gate
Type 2 new material
• Use trigonometry to break the overall initial velocity into its horizontal and vertical parts (components)
• SOHCAHTOA
Type 3
• Is a combination of the other types
• Kicking a soccer ball off the cliff
Assumptions of type 3
• Accelerations of object
• The overall initial velocity has to be broken up into its horizontal and vertical components
• BUT NO OTHER guaranteed assumptions
Example problem for Type 3
• Susan kicks a ball off the top of a 50 m high cliff. It leaves the cliff with a velocity of 65 m/s at an angle of 37° from horizontal. Complete the chart.
Initial Chart
a 0 -9.8
d -50
Initial v
Final v
VH
t
Break apart initial velocity
65 m/s V
H
Cos (37) = (H / 65)
0.799 = H / 65
H = 51.9
Sin (37) = V / 65
0.602 = V / 65
V = 39.1
Chart with initial velocities
a 0 -9.8
d -50
Initial v 51.9 39.1
Final V 51.9
time
VH
Use the vertical information to solve for the FINAL Velocity if
You want to avoid using quadratic equations
Final steps
• Once you get the vertical final velocity
• Then use the easy equation to solve for time
• Then solve for the rest the same way we have always done it in these projectile problems
Projectile work
• You see a set of 5 problems in various parts of the room.
• Go to a set, pick one and begin to solve
• All problems need to be completed for homework and can be found on the internet or as a handout from here at the end of school
Problem #1
A player kicks a football from the ground level with a velocity of magnitude 27.0 m/s at an angle pf 30.0° above the horizontal.
a) find the ‘hang time’, that is the time the ball is in the air.
b) the distance the ball travels before it hits the ground
Problem #2
A player kicks a football from the ground level with a velocity of magnitude 27.0 m/s at an angle pf 60.0° above the horizontal.
a) find the ‘hang time’, that is the time the ball is in the air.
b) the distance the ball travels before it hits the ground
Problem #3
• A beach ball, moving with a speed of +1.27 m/s. rolls off a pier and hits the water 0.75 m from the end of the pier.
How high above the water is the pier?
Problem #4
• A shot put is released with a velocity of 12 m/s and stays in the air for 2.0 s.
a) At what angle with the horizontal was it released?
b) What horizontal distance did it travel
Problem #5
• An archer stands 40.0 m from the target. If the arrow is shot horizontally with a velocity of 90.0 m/s, how far above the bulls-eye must he aim to compensate for gravity pulling his arrow downward?
Answers• Problem #1
a) 2.76 s b)64.5 m
Problem #2a) 4.78 s b) 64.5 nm
Problem #31.7 m
Problem #4a) 55° b) 14m
Problem #5a) 0.966 m
Challenge problem
• A rude tourist throws a peach pit horizontally with 7.0 m/s velocity out of an elevator cage. The elevator is moving upward with a constant velocity of 8.5 m/s velocity.
• How long will it take the peach pit to land on the ground, 17.0 m below his initial position?