GENERAL CERTIFICATE OF SECONDARY EDUCATION
TWENTY FIRST CENTURY SCIENCE PHYSICS A
Unit 3: Ideas in Context plus P7 (Higher Tier) RESOURCE BOOKLET
To be opened on receipt
INSTRUCTIONS TO CANDIDATES • • • • • This booklet contains the article required to answer question 1. Take this article away and read it through carefully. Spend some time looking up any technical terms or phrases you do not understand. For the examination on Wednesday 10 June 2009 you will be given a fresh copy of this article, together with a question paper. You will not be able to take your original copy into the examination with you.
INFORMATION FOR CANDIDATES • This document consists of 4 pages. Any blank pages are indicated.
© OCR 2009 [M/103/3795] SP (NF/SW) V00783/3
OCR is an exempt Charity
2 Sheffield Supertram System
With a length of 34.8 m and a width of 2.65 m, the supertram is one of the largest articulated cars ever built for public transport. An empty supertram has a mass of about 50 000 kg. It can carry 88 people sitting down and an extra 162 passengers standing. The supertram has a top speed of 80 km / h. The momentum change when the supertram pulls away from a stop and reaches top speed is enormous. The steepest hill the supertram goes up and down has a slope of about 1 in 10. A lot of energy is needed for the tram to go up this hill in Sheffield. Going down the hill, the gravitational potential energy of the supertram is mostly converted to kinetic energy. When the regenerative brakes are used to slow down the tram, the kinetic energy is converted to electrical energy. The electrical energy can be stored in batteries or fed back into the tram circuit.
© OCR 2009
3 Electrical power The tram uses electricity to work, usually from overhead cables. The electricity comes from the power supply, along the overhead cables and then flows down a pole. The pole sticks out of the...