Final answer:
The question involves calculations related to the position, velocity, and acceleration of a particle in physics, specifically finding the time when the particle crosses the origin, its displacement over a period, and determining its acceleration and position at different instances when the velocity is a function of time.
Step-by-step explanation:
Understanding Particle Motion
The question regards the motion of a particle along the x-axis and its position as a function of time, described by equations of motion in Physics. In part (a), to find the time when the particle crosses the origin, you would set the position function x(t) = 4.0 - 2.0t to zero and solve for t. In part (b), the displacement is the difference in position from t = 3.0 s to t = 6.0 s, which we find by calculating x(6) - x(3) using the given position function.
In consideration of velocity and acceleration, if a particle's velocity remains a constant 7.0 m/s, its acceleration as a function of time is zero since its velocity does not change. The position at various times is found by integrating the velocity function, or by using the formula x(t) = x0 + vt given the initial position x0 and the constant velocity v.
Finally, when dealing with velocity that varies with time, such as v(t) = A + Bt−1, acceleration is found by differentiating the velocity function with respect to time, and position is obtained by integrating the velocity over the given time, using any known initial positions to solve for constants in the position function.