A 4 m long iron beam of mass 7 kg and cross-sectional area of 2 cm2 is placed ne
ID: 1916007 • Letter: A
Question
A 4 m long iron beam of mass 7 kg and cross-sectional area of 2 cm2 is placed near a furnace and its temperature increases by 300o C. (a) Calculate the net thermal energy absorbed by the beam during this process. (4 points) (b) Find the increase in length of the beam. (3 points) (c) If the beam is attached to rigid supports on both ends and is not allowed to expand, find the force applied to the beam at the supports. (5 points) (d) Which of the following combinations of properties will result in the smallest expansion of a substance due to the absorption of a given amount of thermal energy? (2 points) (i) small c, large ? (ii) small c, small ? (iii) large c, small ? (iv) large c, large ??Explanation / Answer
Net thermal energy absorbed = KAdT/L = 60*2*10^-4*300/4 = 0.9 J/sec As we know ?L = La?T = 12*4*10^-6*300 = 0.0144 m = 14.4 mm As we know E = Stress/Strain 27*10^6 = (F/(2*10^-4))/(0.0144/4) F = 19.44 N