Ch. 5 – Projectile MotionThis chapter has two main categories… Vector motion & Projectile motion…

Always know which one you’re dealing with before any calculations!!!

I. Vector quantities: Measurements that have both magnitude and direction, like velocity.

Scalar quantities have only magnitude, like speed.

A. Consider planes and boats on windy days to see why this is important.

B. Resultant vectors: a combination of two or more directions of vectors, usually angled.

2. Will use three main methods to solve for angled resultant vector.

a. Pythagorean Theorem: (A2 + B2 = C2)

b. 3-4-5 Right Triangles:

1. If the two vectors are in a straight line, either add or subtract them.

Ex. A plane flying at 500 mph into a 55 mph headwind… - or – a plane flying at 500 mph with a 40 mph tailwind.

Ex. A boat moving at 10 m/s with a side current of 7 m/s.

Ex.

c. Parallelogram construction:

**This method is not as exact and is usually just used to get an Idea of size and direction of resultant vector.

II. Projectile Motion: Motion through the air with only gravity as a factor!(neglecting air resistance)

A. The horizontal and vertical vectors act independently of each other!!

Think baseball: pitcher’s mounds and throwing from outfield.

B. Always solve vertical information FIRST, determined by gravity!!!!!

1. Figure out the time the object will be in the air, then everything else!

2. Use free fall equations… v = gt --- d = 1/2gt2

C. Horizontal motion is generally constant – will tell you how far away!

** Use linear motion equations… v = d / t

D. Launching objects through air: Which angle causes greatest distance?

45 degrees – gives greatest horizontal and vertical energy!

E. If an object were to be shot / thrown / launched with enough speed that the dropping curve matched the curve of the Earth, what would it be?

Interestingly enough – complementary angles yield same distance!

THAT’S RIGHT --- A SATELLITE!!!

Falling AROUND an Earth near you!