Day 15 Honors PhysicsIn 2 classes: QUIZ 3 on kinematics, projectiles, vectors and graphs

HQ Q’S?

RELATING IT WEST VIRGINIA STYLEWhat major physics idea so far is always

going to be in either X or Y direction?

GRAVITY! Its only in the Y direction!

In the air: the acceleration in Y is -10m/s2.In the air, the acceleration in X is 0.

Synopsis: Since gravity pulls down, things in air won’t change speed horizontally.

IN DA HALL

CART AND BALL.. You in seatsThe overall motion of the ball:

CART AND BALL.. You on BoardsX Y

POS

VEL

ACC

CART AND BALL.. You in seatsBut what if…. I threw it at a forward

angle?

Would time in air change? How?

Would it reach the same max height?

Would it land at the same place?

Example One:A ball rolls off a horizontal bridge at 5m/s. The bridge is 45m high above water.

We will determine how far from the bridge the ball hit the water at.

PICTURE… with points labeled

Our X and Y tables:

Solution

SUMMARYThings that move HORIZONTALLY

at 1st:

Don’t go up in the air

Have NO Y velocity at 1st, only X velocity

So now watch this clip of a busWhat is wrong with this?

Watch Me Do OneA golf ball is hit with a velocity of

24.5m/s at 35 degrees above the horizontal. Find:◦ Both initial velocities

   

◦ If it ended at the same height, find the distance it landed from the start

 

First the picture AND symmetry

Vi in X and in Y

Our tables

Solution

SUMMARYI always try to identify if I have initial

velocity or not.◦Angles? Find the initial velocities using SIN

and COS◦Horizontally? I can assume no up/down

motion… That means there is NO Y velocity

I always try to determine if a given number or thing I am solving for is HORIZONTAL or VERTICAL.

I make 2 separate tables for X and Y info.

Now… Look at HW, make tables