Air at p 1 atm enters a thin-walled (D 5-mm diameter) long tube (L 2 m) at an inlet temperature of Tm,i 100 C. A constant heat flux is applied to the air from the tube surface. The air mass flow rate is m . 135 106 kg/s. (a) If the tube surface temperature at the exit is Ts,o 160 C, determine the heat rate entering the tube. Evaluate properties at T 400 K. (b) If the tube length of part (a) were reduced to L 0.2 m, how would flow conditions at the tube exit be affected? Would the value of the heat transfer coefficient at the tube exit be greater than, equal to, or smaller than the heat transfer coefficient for part (a)? (c) If the flow rate of part (a) were increased by a factor of 10, would there be a difference in flow conditions at the tube exit? Would the value of the heat transfer coefficient at the tube exit be greater than, equal to, or smaller than the heat transfer coefficient for part (a)? 8.31 T

LECTURE 10 Moment about an axis Moment of a scalar force about any point is to the shortest perpendicular distance To find the moment around an axis (a) We take the dot product of the unit vector of a with (r x F), the cross product of r and F For example, you should set up a problem like so… uax uay uaz rx ry rz Fx Fy Fz ua is the unit vector along the a axis r is the position vector from the a axis to where the force is applied F is the force applied Note: (P x Q) ∙ R = R ∙ (P x Q) LECTURE 11 MOMENT OF A COUPLE A couple is 2 parallel forces with the same magnitude pointing in opposite directions Moment by a couple is defined as Mo = Fd F is the magnitude of the force and d is the perpendicular distance between the