A car starts from rest, moving along a straight line, first with an acceleration a = 5m/s^2 starting from rest, then uniformly and finally decelerating at the same rate 5m/s^2, comes to rest. If the total time of motion of car is 25 s and average velocity during the time is equal to v = 20 m/s . How long does the particle move uniformly? Need step-by-step explanation. No spam. Thanks.

The heliocentric and the geocentric models of the solar system included these central principles

This is the number of complete movements of a wave per second.

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".