A block of mass m = 2 kg is attached to a spring with spring constant k = 200
N/m, and is set to oscillate on a friction-less horizontal surface. At time t = 0 its
position is X0 = 0 and its velocity is v0 = +5 m/s. If the displacement is a cosine
function, X(t)=A cos(wt+p), then which answer is correct about the oscillation
amplitude A and the phase constant, p.:

What is the earliest point in the universe that we can observe? why can’t we see back further than this?

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).

Is there a point between a 10 nc charge and a 20 nc charge at which the electric field is zero?