1. 1.4: Simple Types of Motion: Having the initial conditions(initial position and initial velocity), what is the distance and speed at later time? a. No Motion: V=0 and a=0 t v ta b. Constant Velocity: (Uniform Motion) Object covers equally distances in equally times Constant speed in certain direction. t x t a t v Slope=rise/run =v c. Constant Acceleration: Object changes its velocity at fixed rate. xt

2. t=0 t=1s t=2s t=3s t=4s V=39.2m/sX=0 V=0m/s V=9.81m/s V=19.6m/s V=29.4m/sX=34.2m X=58.8m X=73.5m X=78.5m Motion up t x Motion down t v Slope=9.81m/s 2 Slope=-9.81m/s 2 t a 9.81 -9.81

3. a=  v/  t=v-v intial /t V=v intial +at v t v intial Since the v-t relationship is linear v ave =(v intial +v)/2 V ave =  x/  t=x/t X=v ave t=(v intial +v)t/2 X=v intial t+at 2 /2 x=(v intial +v intial +at)t/2 x=(v+v-at)t/2 X=vt-at 2 /2 Solving for v intial Solving for v final v intial vv at The position,the velocity and the acceleration for a car starts at rest, accelerates for an interval, then moves with constant velocity,and then brakes with negative acceleration to rest again. Relative Acceleration! Constant speed a=0 Braking a<0 Resting a=0 Accelerating a>0 Resting a=0 x t t t v a

4. Newton’s laws : What causes the motion? Force: A push or a pull acting on a body Units of force: Newton, dyne,..etc. 1 Newton: is the force when acts on a particle of mass 1kg, the particle gain acceleration 1m/s2. 1 Dyne: is the force when acts on a particle of mass 1g, the particle gain acceleration 1cm/s2. 1N=1kg  1m/s21 dyne=1g  1cm/s2 Q: Show that 1N=10 5 dyne? Weight: The force due to gravity. c M m F g =w Q:A person has weight 500N on the earth, what is his weight on the moon? Friction : resistance force for the relative motion. Static friction: when there is no relative motion. Dynamic friction: When there is a motion. w w Location – mass –weight Earth 1kg 9.8N Moon 1kg 1.6N Space 1kg 0N

5. 2.2 Newton’s First Law of motion: Isaac Newton : (1642-1727) His three laws of motion first appeared in his book called Principia. A body remains at rest or moves in a straight line at a constant speed unless acted upon by a force. At rest or moving with uniform velocity The force laws The laws of motion Newton’s laws F F1 F2 F1 F2 F total EnvironmentForcebodyAcceleration

6. Particle initially at rest: the particle will start move when the external force is greater than the (static)friction force. Particle initially is moving: 1.constant net force in its direction of motion:Particle accelerate 2.constant net force opposite to its direction of motion:Particle decelerate 3.constant net force perpendicular to its direction of motion: Uniform circular motionCentripetal force w F fsfs N Kinetic friction 2.3 Inertial mass and gravitational mass : g doesn't depend on mass Galileo 1600’s Pisa w FkFk air resistance w FsFs N Parked car

7. 2.4 Newton’s Second law of motion: The acceleration of an object is directly proportional to the net force acting on the object, and inversely proportional to the mass of the object. F m F a m F a/2 m a/3 m m m F a m m m 2F 3F 2a 3a a  1/maFaF F =ma The total external force acting on a particle equals Its mass times its resultant acceleration. Inertial mass and gravitational mass Revisited F=ma, m is the inertial mass W=mg, m is the gravitational mass Since F=w in the free fall and a=g then the inertial mass and the gravitational mass are equal.

8. Thank You How the idea occurred to Einstein: “I was sitting in a chair in the patent office in Bern when all of a sudden A thought occurred to me: If a person falls freely he will not feel his own Weight. I was startled. This simple thought made a deep impression on me. It impelled me toward a theory of gravitation.”