Unit 2: Motion in 2D. Textbook: Chapter 3 & Chapter 4. Unit Objectives: Motion Models. Recognize that an object in free fall will accelerate at a constant rate of 9.8 m/s 2 downward near the surface of the earth. Use kinematic equations to determine velocity or position at any time
Chapter 3 & Chapter 4
a) y-x, y-t, x-t, vx – t, vy- t, ax-t, ay-t
In 1971, the commander of Apollo 15 confirmed this concept by dropping a hammer and a feather. Both hit the ground at the same time.Free Fall on the Moon
Then vector B, which is twice as long, would represent a displacement of six kilometers to the north!Magnitude of Vectors
Ax = Acos Ay = Asin
Bx = Bcos By = Bsin
a = -3 & b = 10
Resultant: 599 m @ 1o
Equilibrant: 599 m @ 181o
Sprint (-6, -2) blocks
1- A baseball outfielder throws a long ball. The components of the position are x = (30 t) m and y = (10 t – 4.9t2) m
2- A particle undergoing constant acceleration changes from a velocity of 4i – 3j to a velocity of 5i + j in 4.0 seconds. What is the acceleration of the particle during this time period? What is its displacement during this time period?
The components vix & viy are not necessarily positive. If an object is thrown downward, then viy is negative.
tPosition graphs for 2-D projectiles. Assume projectile fired over level ground.
1) Uniform motion at constant velocity in the horizontal direction
2) Free-Fall motion in the vertical direction
What is the velocity function of the plane?
What is the velocity at t = 2 seconds?
Just like in 1-D, take the derivative of the position function, to get the velocity function.
Take the double derivative to find acelleration…
The woman is using the surface of the Earth as her reference frame. She considers herself and the train platform to be stationary, while the train is moving to the right with positive velocity.
If now, the perception of motion is from Ted’s point of view (man in the train). He uses the inside of the train as his reference frame. He sees other people in the train as stationary and objects outside the train moving back with a negative velocity.
Inertial Reference Frames
v = 15 m/s
VBS = 3.35 m/s at 63.4 degrees