In order to measure the properties of a battery, several resistors are connected to the battery in series and the terminal voltage is measured. In the first case, the resistor has resistance R1 = 3.5 Ω and the terminal voltage is ΔV1 = 2.9 V. In the second case, the resistor has resistance R2 = 77 Ω and the terminal voltage ΔV2 = 7.5 V. Required:
Find the numerical value of r in Ω.

Part f - example: finding two forces (part i) two dimensional dynamics often involves solving for two unknown quantities in two separate equations describing the total force. the block in (figure 1) has a mass m=10kg and is being pulled by a force f on a table with coefficient of static friction îľs=0.3. four forces act on it: the applied force f (directed î¸=30â above the horizontal). the force of gravity fg=mg (directly down, where g=9.8m/s2). the normal force n (directly up). the force of static friction fs (directly left, opposing any potential motion). if we want to find the size of the force necessary to just barely overcome static friction (in which case fs=îľsn), we use the condition that the sum of the forces in both directions must be 0. using some basic trigonometry, we can write this condition out for the forces in both the horizontal and vertical directions, respectively, as: fcosî¸â’îľsn=0 fsinî¸+nâ’mg=0 in order to find the magnitude of force f, we have to solve a system of two equations with both f and the normal force n unknown. use the methods we have learned to find an expression for f in terms of m, g, î¸, and îľs (no n).

The first law of thermodynamics states that heat added to a system is neither created nor destroyed but is as it changes into other forms of energy.

The statue of liberty is 305.5 feet high. when the angle of elevation of the sun is 50 , what is the distance to the tip of the shadow from a point at water level and directly below the highest point of the statue?