1. A child swings a toy of mass 0.05 kg on a string of length 1.9 m in a horizontal circle at constant speed so that the string is nearly horizontal. The toy has a period of 0.6 s. The amount of centripetal force in the string is most nearly (A) 2 N (B) 5 N (C) 10 N (D) 20 N

2. For the same toy in a circular path as the previous problem, the net centripetal force on the toy and its acceleration are
(A) both radially inward. (B) perpendicular to each other. (C) both zero. (D) both tangent to the circle.

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).

What is the final velocity of the initial velocity of 25 and -50?

Give an example in which the electrical energy changes to light energy