Schedule Today: Friday Feb 9th: Monday Feb 12th: Review of Material in Quiz 1 on Units 1 and 2 Start Unit 3: Force and the Laws of Motion Friday Feb 9th: No class, use the time to study for the test Monday Feb 12th: Quiz #1 Problem sets for Units 1 and 2 due. 1/18/2019 Physics 253

Material to Master Unit 1: Measurement and Motion How to assign significant figures and calculate relative uncertainty. Conversion of units. Use of dimensional analysis. The equations of motion for constant acceleration. Analysis of problems in free-fall. Unit 2: Vectors and 2-D Motion Unit vectors and vector addition. The equations of motion for projectile motion Analysis of problems of projectile motion. 1/18/2019 Physics 253

Read & access the problem Setup Read & access the problem Draw a diagram with coordinate system, choose + and - directions Create a table of known and unknown quantities Manipulation of Equations Consider the physics involved Select appropriate equation or equations Do required calculations Check you work Does it pass the smell test Do the units make sense? 1/18/2019 Physics 253

Idealized motion (where air resistance is neglected and the acceleration is constant) is known as freefall. The magnitude of the acceleration due to gravity at the earth’s surface is denoted: Since the acceleration is constant we can apply the equations of motion! Because objects fall in the vertical or y direction it's also natural to use the symbol y for displacement g = 9.80 m/s2 or 32.2 ft/s2 1/18/2019 Physics 253

Vy=Vyj Vx=Vxi Vz=Vzk V V = Vxi + Vyj + Vzk 1/18/2019 Physics 253

Power of Unit Vectors Now it’s a snap to add and subtract vectors! One just adds the coefficients of the units vectors. Later on we’ll learn about other key operations that are facilitated by unit vectors such as dot and cross products. 1/18/2019 Physics 253

Kinematic Equations for Projectile Motion (+y up, ax =0, ay=-g= -9 Kinematic Equations for Projectile Motion (+y up, ax =0, ay=-g= -9.8m/s2 1/18/2019 Physics 253

1/18/2019 Physics 253