4. A variable force (in Newtons) acting on an object is represented by the function F(x) = x2 - 4x +7, where x is the distance in meters from the origin. How much work is required to move the object from X = 1 to x=4? 5. The velocity of a particle P, at time t seconds after passing through the origin, O is given by the formula: v= 6t - to + 12ms'. Find: a) The acceleration of the particle P, when its velocity is 21ms'. b) The time at which the particle, P returns to the origin, O. given that the particle moves in a straight line