Exercise 4: A light string ABCDE whose extremity A is fixed, has weights \( \mathrm{W}_{1} \) and \( \mathrm{W}_{2} \) attached to it at B and C . it passes round a small smooth peg at D carrying a weight of 300 N at the free end E as shown. If in the equilibrium position, BC is horizontal and AB and CD make \( 150^{\circ} \) and \( 120^{\circ} \) with BC . Find (a) tensions \( \mathrm{AB}, \mathrm{BC} \) and CD for the string and (b) magnitudes of \( \mathrm{W}_{1} \) and \( \mathrm{W}_{2} \)

What requirements must be met for a nuclear fu- sion reaction to occur? A select all that apply. A extremely low temperatures C extremely high temperatures D a large amount of pressure

uat medan listrik di suatu titik \( P \) yang itimbulkan oleh sebuah muatan \( q \) di titik asal \( O \) :

- Una pelota es lanzada verticalmente hacia arriba. La altura alcanzada por la pelota (h, expresada en metros) función del tiempo (t en segundos), está dada por la siguiente formula: \( h(t)=-t^{2}+6 t+7 \) a) ¿Desde qué altura fue lanzada la pelota? (tiempo cero) b) Indicar la altura máxima que alcanza la pelota, ¿Luego de cuántos segundos alcanza dicha altura? c) ¿Cuántos segundos pasaron hasta que la pelota toca el piso?

Bandgap and photodetection (a) Determine the maximum value of the energy gap which a semiconductor, used as a photoconductor, can have if it is to be sensitive to yellow light ( 600 nm ). (b) A photodetector whose area is \( 5 \times 10^{-2} \mathrm{~cm}^{2} \) is irradiated with yellow light whose intensity is \( 20 \mathrm{~mW} \mathrm{~cm}^{-2} \). Assuming that each photon generates one electron-hole pair, calculate the number of pairs generated per second.

If the half-life of \( 1-131 \) is 7.4 days, how many days would it take for only \( 3.2 \times \) \( 10^{-2} \) grams of \( 1-131 \) to be left in Mr. Miller's body if Dr. Goodie started him on an initial dose of 5.5 grams? (Round your answer to two decimal points)