Projectile Motion Circular Motion Relative Motion PHYS116 A02

Projectile Motion, Circular Motion, Relative Motion PHYS-116 A-02, 9/6/11, Lecture 4 Momchil Velkovsky

Position and velocity vectors

How to calculate: x and y (and z) components do not speak to each other! vx= – (0. 5 m/s 2) t vy=(1. 0 m/s) + (0. 075 m/s 3)t 2 We can find x and y independently! x=2. 0 m – (0. 25 m/s 2)t 2 y=(1. 0 m/s)t+(0. 025 m/s 3)t 3

Acceleration

What is the direction of the rover’s average acceleration vector for the time interval from t = 0. 0 s to t = 2. 0 s? ¡ ¡ ¡ A. up and to the left B. up and to the right C. down and to the left D. down and to the right E. none of the above

Our rover again vx= – 0. 5 m/s 2 t vy=(1. 0 m/s) + (0. 075 m/s 3)t 2 We can find ax and ay independently! Acceleration: ax= – 2. (0. 25 m/s 2) ay=6. (0. 025 m/s 3)t

Acceleration of the rover

Motion with Constant Speed

Parallel and Perpendicular components of acceleration

The motion diagram shows an object moving along a curved path at constant speed. At which of the points does the object have zero acceleration? ¡ ¡ ¡ A. point A only B. point C only C. point E only D. points A and C only E. points A, C, and E

A scientist aims an anesthesia dart towards a monkey. The monkey drops at the moment the scientist shoots. Will the dart hit the monkey? 1. 2. Yes No

When the dart is at point P, where will be the monkey? 1. 2. 3. A B C

A motorcycle jump y x

Watering your garden

An object moves at a constant speed in a clockwise direction around an oval track. The geometrical center of the track is at point O. When the object is at point P, which arrow shows the direction of the object’s acceleration vector? ¡ ¡ #1 #2 P #5 Oval track #3 #4 O ¡ A. #1 (directly away from O) B. #2 (perpendicular to the track) C. #3 (in the direction of motion) D. #4 (directly toward O) E. #5 (perpendicular to the track)

Centripetal acceleration

A Ferries wheel turns with 5 RPM. At points A, B and C, the acceleration is: |a. A|>|a. B|>|a. C| |a. A|<|a. B|<|a. C| |a. A|=|a. B|=|a. C| 1. 2. 3. A B C

Newton’s First Law, Inertial Reference frames

Relative motion

The monkey again y h v 0 x v 0 y l x

Next time Reading : Chapter 5 ¡ I’ll assign the next reading question and the next homework (for Monday). ¡ On Thursday I’ll give you extra practice problems. ¡