26 Costante di gravitazione universale La costante di Newton \( G \), che compare nell'espressione della forza gravitazionale, vale: \( G=(6,673 \pm 0,010) \cdot 10^{-11} \mathrm{~m}^{3} /\left(\mathrm{kg} \cdot \mathrm{s}^{2}\right) \) Nota che nelle misure di precisione l'errore è talvolta riportato con due cifre significative. Qual è l'errore percentuale su \( G \) ?

body placed on a rough horizontal level \( W=75 \mathrm{~N} \) horizontal force affected 50 N Makes it about to move en the coefficient of friction equals \( \begin{array}{llll}\text { 1) } \frac{1}{3} & \text { 2) } \frac{2}{3} & \text { 3) } \frac{3}{4} & \text { 4) } \frac{1}{4}\end{array} \)

QUESTION 1: EPICYCLIC GEAR AND GEAR TRAINS An epicyclic gear train has a sun wheel with 24 teeth, and two planetary wheels of 46 teeth each, The latter mesh with the internal teeth of a fixed annulus with 116 teeth. The input shaft, carrying the sun wheel, transmits \( 4,5 \mathrm{~kW} \) at \( 280 \mathrm{r} / \mathrm{min} \). The output shaft is connected to an arm L that carries the planetary wheels. Calculate the speed of the output shaft.

4. When you descend in a plane, your ears pop. Is air moving into your ears or out of them when they pop? 5. Explain why a balloon gets bigger as you put more molecules of gas into it at a constant temperature.

Question 6/13An air tank is exposed to ambient temperature.If you set the air pressure of the tank to 35 psi for a leak test and find that 24 hours later the tank's pressure has increased, what could've happened?The tank leakedThe tank drew in additional airThe ambient temperature increasedThe ambient temperature decreased

b. Un moteur consomme \( x \) litres d'essence de masse volumique \( \rho \) et de pouvoir énergétique \( H \) en heures. 1. Quelle est la puissance \( P \) de ce moteur? 2. Trouverais-tu une valeur plus faible ou plus élevée si tu tenais compte des pertes d'énergie? c. Un thermoplongeur de puissance \( P \) permet de chauffer une masse \( m \) de liquide de chaleur massique c de la température \( T_{7} \) à \( T_{2} \) en un temps \( t \). 1. Exprime la masse de liquide chauffée par ce thermoplongeur. 2. Exprime la température \( T_{2} \) du liquide.