Out into space 2
- 2. ANSWER: • IF BOTH SATELLITES HAD THE SAME MASS, THEN THE ONE TWICE AS FAR WOULD BE ATTRACTED TO THE STAR WITH ONLY ONE QUARTER THE FORCE (INVERSE -SQUARE LAW). • SINCE THE FORCE IS THE SAME FOR BOTH, THE MASS OF THE FARTHERMOST SATELLITE MUST BE FOUR TIMES AS GREAT AS THE MASS OF THECLOSER SATELLITE.
- 3. FIELDS, FIELD LINES & FIELD STRENGTH Out into Space Lesson 2
- 4. LI… • Represent force fields using field lines • Describe field strength • Solve problems using field strength
- 5. FORCES • Contact forces • Pick up the ball or kick it • What happens to the ball? • What is the source of this contact force? • Weight • Drop the ball • What happens to the ball? • What is the source of this force?
- 6. FIELDS • The region of space surrounding a body where other bodies will feel a force due to it. • Magnetic Field • Region of space around a magnet where magnetic materials will feel a force. • Electric Field • Region of space around a charge where other charges will feel a force. • Gravitational Field • Region of space around a mass where other masses will feel a force.
- 7. GRAVITATIONAL FIELDS • Infinite but weak • Why? • Invisible • Untouchable • Drawable? A model?
- 8. FIELD LINES • The direction of a field line at a point gives the direction of a force on a small mass at that point. • Closer the lines the stronger the field. • Describe the variation in strength of a radial field.
- 9. FIELD LINES • Really 3D • Radial From space • Towards centre of the earth • On surface parallel and equidistant (field is uniform) • Cannot cross (add them as vectors) Near surface
- 10. MEET THE G’S BIG G LITTLE g GRAVIATIONAL FIELD STRENGTH F = G m1 m2 r2 • Intrinsic strength of a gravitational field. Force exerted by that field on one kilogram of mass. • g=W/m • If we substitute this into F = Gm1m2/r2 • The universal gravitational constant as used in • • • Where F=W then Really very small 6.67x10 -11 N m2 kg-2 g = GM/r2 • On Earth’s surface g = 9.81 N/kg (variable)
- 11. ANALYSING DATA FROM THE APOLLO 11 MISSION TO THE MOON • Apollo 11 was the spaceflight which landed the first humans, Neil Armstrong and Edwin "Buzz" Aldrin, Jr, on Earth's Moon on July 20, 1969, at 20:17:39 UTC. The United States mission is considered the major accomplishment in the history of space exploration. resurecfulphysics.org
- 12. A LARGE-SCALE EXPERIMENT IN SPACE • Detailed data is kept of every space flight. These data, giving speeds and distances of Apollo 11 as it went to and returned from the Moon, are extracted from data supplied by NASA. They can be thought of as the results of an experiment to probe Earth’s gravitational field.