2. Planet Earth Force Laws in Nature - Dynamics kinds - sources - strengths - ranges - mediators

3. Review Newton’s Laws –Law of Inertia - definition of mass –F = ma –mutual interaction These give the existence and strength of all forces There seems to be a myriad of forces we deal with each day - they all can be related to just 4!

4. Force Laws Gravity Electricity and Magnetism Strong Nuclear Weak Nuclear

5. Gravity Force Distance behavior source of the force –cause? receiver - what can feel the force 1/r 2 gravitational charge - mass (m) F = Gm 1 m 2 /r 2 ATTRACTIVE ONLY - LARGE SCALE STRUCTURE/ STABILITY OF THE UNIVERSE

6. Electric force Distance source receiver 1/r 2 charge(q) F= kq 1 q 2 /r 2 ATTRACTIVE AND REPULSIVE - STABILITY OF THE ATOM/MOLECULES/MATTER

7. Strong Force Distance source receiver Scotch tape 10 -13 cm many “charges” ?????????????? ATTRACTIVE AND REPLUSLIVE STABILITY OF ATOMIC NUCLEOUS

8. Weak Force Distance source receiver Scotch tape 10 -16 cm many “charges” ???????????????? Radio active decay - instability of matter

9. Range Gravity E & M Strong Weak Infinite Short 10 -13 cm Very short 10 -16 cm

10. Strength Strong E & M Weak Gravity 1 10 -2 10 -13 10 -42

11. Mediators Strong E & M Weak Gravity Gluons Photons Weakons Gravitons Exchange particles (1949) vs. Action at a distance /field concept (19th century)