Question
b. What is the total time for the jumper to slow down from 25m/s to zero? 6. A super tanker coming west into port started accelerating 2.0 hours before arriving. If the ship slowed at 25km/h^2 [E] before coming to a stop, what was the initial velocity?
Solution
4.6
(197 Votes)
Zachariah
Expert · Tutor for 3 years
Answer
**b. Calculating Time to Slow Down**Here's how to calculate the time it takes for the jumper to slow down:* **We need more information.** The problem only gives us the initial velocity (25 m/s) and the final velocity (0 m/s). To calculate the time, we also need the *acceleration* (or deceleration, which is just negative acceleration) experienced by the jumper. The formula we'd use is: * v_f = v_i + at Where: * v_f = final velocity (0 m/s) * v_i = initial velocity (25 m/s) * a = acceleration (which we need) * t = time (what we want to find)* **Example:** Let's say the jumper's deceleration is -2 m/s². Then the calculation would be: * 0 = 25 + (-2)t * -25 = -2t * t = 12.5 seconds**6. Calculating Initial Velocity of Super Tanker**Here's how to calculate the initial velocity:* **Understand the problem:** The ship is decelerating eastward, which means its initial velocity was westward.* **Use the correct formula:** We can use the following kinematic equation: * v_f = v_i + at Where: * v_f = final velocity (0 km/h, since the ship comes to a stop) * v_i = initial velocity (what we want to find) * a = acceleration (-25 km/h² East, which is equivalent to +25 km/h² West since it's slowing down) * t = time (2.0 hours)* **Solve for v_i:** * 0 = v_i + (25 km/h²)(2.0 h) * 0 = v_i + 50 km/h * v_i = -50 km/h* **Interpret the result:** The negative sign indicates the initial velocity was westward, as expected. Therefore, the initial velocity of the super tanker was **50 km/h [W]**.