Question

A small metal bar, whose initial temperature was 20° 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 2º 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.) sec Need Help? Read It Read It Watch It Watch It Talk to a Tutor Talk to a Tutor

Answer 1

1 29.140 16 the rate of change in temparature is directly proportional to the difference in their temparature Temparature of metal bar = o _ on_water a100% di = K (0-100) 9_lo0-100) KU+ lace). 7 0-100 = c eft > O=100+ ceft at t=0, 0= 20° c = -so @ at t=L, 0=22 » 22 = 100 soek 2) 78 = - soek 4 K -18 3940- > ek = $% or K=UW39) 1) 0 = 762c, t= ? - 70 = 100 - so eht * +30/80 = eht en (948)=_kt ta__ luchd) - 2 In (3/8) t= 77 Seands. en (3/4) 2 PL o = 9800 t = a ln (ud) - 291.40 sands In 139/40) = 4.86 minutes appuaineafely. - & I