Use equation (2.190) to show that the razor-thin disk for which the circular speed is given by (2.262a) has surface density (toomre 1963) 1 σ(r ) (2.262b) v1 a2/r2 2tgr show that these formulae correspond to the mestel disk in an appropriate limit. show that the surface density (2.68b) of the kuzmin disk is obtained when £(r) is differentiated with respect to a2, and hence recover the circular speed of this model

Asmall metal bar, whose initial temperature was 10° c, is dropped into a large container of boiling water. how long will it take the bar to reach 70° c if it is known that its temperature increases 2° during the first second? (the boiling temperature for water is 100° c. round your answer to one decimal place.) sec how long will it take the bar to reach 98° c? (round your answer to one decimal place.)

Question 7 [2 marks] in the circuit below, the electromotive force generated by the battery is e = 6.0 v, and the resistances are r1 = r4 = 1.0 q, r2 = r3 =2.0 q. r. the power delivered by the battery to the circuit is closest to a. 6 w в. 12 w с. 15 w d. 18 w e. 20 w final exam autumn 2014 page 5 of 9 68037 physical modelling faculty of science [2 mark] question 8 with reference to question 7, the current through resistor r2 is closest to a. 1 a в. 2 а c. 3 a d. 4 a e. 6 a

Which of the following is an example of units for speed