Grandma jones is trying to load a wooden crate full of apples into her truck. to accomplish this, she plans to slide the crate up along a board. if the crate has a mass of 50 kg and the board is at an 30º incline, what is the maximum force she must apply parallel to the board to move the crate at constant velocity into her truck if the coefficient of friction is 0.25?

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".