The formula used is: g = G mplanet Rplanet2
Where; g is the acceleration due to gravity, G is Newtons Gravitational Constant, mplanet is the mass of the planet, and Rplanet is the radius of the planet
2) Assess the contribution of Goddard to the development of space exploration
“Dr Robert Hutchings Goddard had no peers. He was the first. He was ahead of everyone in the design, construction and landing of liquid fuel rockets which eventually paved the way into space” – Wernher von Braun * Dedicated his life to developing rockets * Proved rockets can travel through vacuum * Known as the father of modern rocketry - most ideas incorporated into modern rocket designs * Suggested liquid hydrogen and oxygen as ideal rocket fuel – launched world first liquid fuel rocket * 200 patents * 1926 -1941 conducted 100+ rocket tests * Studied rocket combustion chambers, propellant feed systems, fuel nozzles, multistage rockets, parachute recovery, guidance systems (gyroscope) and pressurised fuel reservoir 3) Explain how induction is used in cooktop in electric ranges
Induction cooktops in electric ranges heat a conductive material by producing eddy currents within the material.
Eddy currents are electrical currents induced within conductors by a changing magnet field in the current
Alternating currents passing through the coil under the cooktop result in a rapidly changing magnetic field.
Eddy currents are induced in the metal saucepan above the cooktop.
The resistance of the metal in the saucepan transforms the induced electricity into heat energy and this cooks the food.
4) Describe the competition between Westinghouse and Edison to supply electricity to cities
Edison begun a business setting up DC system of electrical power distribution in NYC, but as DC cannot be transformed (its transmission distance is severely limited).
Westinghouse in 1886, set up an AC generating system, invented by Tesla applying Tesla’s transformers to transmit at high voltage before lowering for household use.
Edison used a smear campaign against Westinghouse:
Lobbying politicians to pass laws prohibiting use of AC above 250V, while 800 for DC.
Conducted public experiments electrocuting animals with AC proving it was unsafe
Recommended AC for electric chair, (called Westinghouse chair and people to be “Westinghouse”)
First attempt at electrocution failed so Edison lost his credibility because of his vocal support for AC.
Westinghouse won World Fair Contract (undercutting Edison’s $1million bid by half).
When president Cleveland pressed a button 100,000 lights powered by AC generators, the 27million people visiting were impressed.
From then on 80% of new electrical appliances were built for AC
5) Discuss the need for transformers in the transfer of electrical energy from a power station to its point of use
Power Stations are usually situated large distances from consumers, presenting problems with power loses in transmission lines (long conductors with high relsistance ie large voltage drop when carrying current - decreased voltages for consumer)
* are needed to reduce power loss; power loss in lines is proportional to = I2R; the lower the current, the lower the energy losses. * the power produced by generators at power station is stepped up by transformers to very high voltages (220-550kV) before being transmitted * at substations step down the voltage to required value before it can be used by household/industry consumers. * enable electricity to be supplied over large distances without wasting too much energy * if not used, powerstations would either be situated in cities, or consumers located near powerstations. 6) Discuss Einstein’s and Planck’s differing views about whether science research is removed from social or