Aseries of measurements of a physical quantity gave us the following numbers (in some unit): 2. 17.47468 17.47392 17.47616 17.47499 17.47257 a. calculate the best estimate of the physical quantity (i. e. calculate the mean value of b. calculate, using the standard deviation method, the error on the considered c. write the error keeping only one significant figure. (it's may be safest to always d. write the final result (i. e. best estimate+ absolute error). the series of measurements) quantity. round up the error).

Find v(t), given acceleration a(t)=7j and initial velocity v(0)=k

Ablock having mass m slides down an inclined plane. the force of friction between the block and the inclined plane is f, the block's weight is m g, and the normal force is n. (a) draw a free – body force diagram showing the forces acting on the block. (b) write down all relevant newton’s equations for a given situation.

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".