Physics 4 Feb 7 2017 P 3 Challenge
Physics 4 – Feb 7, 2017 P 3 Challenge – Solve for the currents in the circuit shown if R 1 = 7 , R 2 = 6 , R 3 = 4 , 1 = 9 V and 2 = 12 V. (Hint: Get out #23 -29 for HWK check apply Kirchhoff’s Rules)
Objectives/Agenda/Assignment Objective: Ch 10. 1 Fields - gravitational Assignment: p 412 #1 -8 Agenda: Homework Review Gravitational fields
Field Forces that act at a distance without any real physical contact are called field forces. There are two field forces: gravitational and electrical forces. Each of these forces exert their effects over space and can be said to correspond to a field times a small unit quantity. We will practice field related ideas with gravitational fields first, then look at the corresponding electric fields with the added twist of positive and negative unit quantities.
Gravitational fields
Gravitational Field Diagrams The gravitational field around a point mass is radial. The density of lines is qualitatively related to the size of the gravitational field. Gravitational field is a vector directed toward the point mass Because gravity is an attractive force, the field the arrows on the diagram are also directed toward the point mass. Gravity is also a conservative force, meaning that the work done in moving between any two points is path independent.
More about work, in general
Work from infinity…and beyond
Gravitational potential energy
Gravitational potential
Summary of important formulas Quantity Force (Law of gravitation) (Vector) (Negative means attractive force) Gravitational field (Vector) Work done by gravity ( to r) (Scalar) Work done by external force ( to r) (Work done to move mass to r) (Scalar) Gravitational potential energy (Scalar) Gravitational potential (Scalar) Equation Relating variables
Gravitational problems Calculate the difference in the gravitational potential energy of a satellite of mass 1500 kg when it is taken from the surface of the Earth to a distance of 520 km above the Earth’s surface. (Me = 5. 97 x 1024 kg, Re = 6. 38 x 106 m, G = 6. 67 x 10 -11 Nm 2/kg 2) What is the gravitational potential at each of those two points, the Earth’s surface and 520 km above the Earth’s surface?
Exit slip and homework Exit Slip – What is the gravitational potential at a distance from Earth’s center equal to 3 Earth radii? (Me = 5. 97 x 1024 kg, Re = 6. 38 x 106 m) What’s due? (homework for a homework check next class) Ch 10. 1 p 412 #1 -8 What’s next? (What to read to prepare for the next class) Read Ch 10. 1 p 396 -412
- Slides: 12