Final answer:
In Physics, the speed and displacement of a cell phone dropped from a descending hot air balloon are determined by the initial velocity, gravity's acceleration, and time since the drop. Simple kinematic equations are used to find these values.
Step-by-step explanation:
The subject of the question is Physics, specifically concerning motions such as free fall and projectile motion, which falls under the category of classical mechanics. As a student has dropped their cell phone from a descending hot air balloon, we are asked to calculate the speed of the phone after 4 seconds and the distance below the balloon it has reached in that time frame. The force of gravity is the primary influence on the phone once it has been dropped, given that air resistance can be ignored as the question suggests. To answer part (a) about the speed of the cell phone after 4 seconds, we use the formula for velocity in free fall: V = V0 + g*t, where V0 is the initial velocity, g is the acceleration due to gravity (9.8 m/s2), and t is the time. Since the balloon is descending, the initial velocity of the phone is -2.44 m/s (negative because it's moving downwards). Therefore, after 4 seconds, the phone's speed is V = -2.44 m/s + (9.8 m/s2 * 4 s). For part (b), calculating how far the cell phone is below the balloon after 4.00 seconds requires the formula for displacement in free fall: d = V0*t + (1/2)*g*t2. The initial velocity, time, and acceleration due to gravity are already known, so the displacement can be calculated.