2. El sistema de paredes se encuentra entre las temperaturas extremas de \( 100^{\circ} \mathrm{C} \) y \( 40^{\circ} \mathrm{C} \). Calcule el coeficiente de conductividad térmica de la pared central, sabiendo que las paredes primera y tercera tienen \( K=0.025 \frac{\mathrm{Cal}}{{ }^{\circ} \mathrm{Ccmseg} \text {. }} \) Todas las paredes son cuadradas de lado 10 cm . y espesor 2 cm .

22.Sebuah benda bermuatan \( \mathrm{q}=9 \times 10^{-5} \mathrm{C} \) dan mempunyai gaya elektrolisis \( 7,2 \mathrm{~N} \). maka kuat medan pada tempat benda tersebut berada adalah.. A. \( 1,2 \times 10^{-6} \mathrm{~N} / \mathrm{C} \) B. \( 4,2 \times 10^{-6} \mathrm{~N} / \mathrm{C} \) C. \( 5,0 \times 10^{-6} \mathrm{~N} / \mathrm{C} \) D. \( 8,0 \times 10^{-6} \mathrm{~N} / \mathrm{C} \)

f Steve throws the football 50 meters in 3 seconds, what is the average speed of the football? (nearest hundredth) If it takes Ashley 3 seconds to run from the batters box to first base at an average spe of 6.5 meters per second, what is the distance she covers in that time? \( \begin{array}{l}\text { Bart ran } 5000 \text { meters from the cops and an average speed of } 8 \text { meters/second before } \\ \text { he got caught. How long did he run? }\end{array} \)

What is the dot product of vector \( j \) with a magnitude of 4 and a direction of \( 30^{\circ} \) and vector k with a magnitude of 10 and a direction of \( 15^{\circ} \) ? (Round your answer to the nearest tenth.)

85 Un pannello di MDF, una fibra di legno utilizzata per mobili componibili, ha spessore \( (14,0 \pm 0,2) \mathrm{mm} \) e forma rettangolare con lati \( (60,0 \pm 0,1) \mathrm{cm} \mathrm{e}(80,0 \pm 0,1) \mathrm{cm} \); la sua massa è \( (5600 \pm 20) \mathrm{g} \). Le specifiche del prodotto in- dicano che il materiale ha densità \( 850 \mathrm{~kg} / \mathrm{m}^{3} \), con tolle- ranza dell'1\%. Calcola la densità del pannello in base ai valori mi- surati. L'indicazione delle specifiche può essere ritenuta cor- retta (cioè il valore ottenuto si discosta al massimo dell' \( 1 \% \) dal valore indicato)? \( \left[(830 \pm 20) \mathrm{kg} / \mathrm{m}^{3}\right. \); si]

1. A 0.500 g (small) mass on the end of a 1.70 m long string is pulled aside \( 20^{\circ} \) from the vertical and shoved downward (toward the bottom of its motion) with a speed of \( 2.4 \mathrm{~m} / \mathrm{s} \). (a) Is the angle on the other side greater than, less than, or the same as the angle on the initial side \( \left(20^{\circ}\right) \) ? Explain in terms of energy. (5pts) (b) Calculate the angle it goes to on the other side, neglecting air resistance. ( 10 pts )