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?