/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 27 A cruise ship with a mass of \(1... [FREE SOLUTION] | 91Ó°ÊÓ

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A cruise ship with a mass of \(1.00 \times 10^{7} \mathrm{kg}\) strikes a pier at a speed of \(0.750 \mathrm{m} / \mathrm{s}\). It comes to rest after traveling 6.00 \(\mathrm{m}\), damaging the ship, the pier, and the tugboat captain's finances. Calculate the average force exerted on the pier using the concept of impulse. (Hint: First calculate the time it took to bring the ship to rest, assuming a constant force.)

Short Answer

Expert verified
The average force exerted on the pier is approximately \(9.375 \times 10^5 \mathrm{N}\) in the opposite direction to the initial motion of the ship.

Step by step solution

01

Calculate the initial momentum of the ship

First, we need to find the initial momentum of the ship. Momentum (p) is given by the product of mass (m) and velocity (v): \[p = m \times v\] Using the given mass and velocity: \[p = (1.00 \times 10^{7} \mathrm{kg}) \times (0.750 \mathrm{m}/\mathrm{s})\] Calculating the value of p: \[p = 7.50 \times 10^6 \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}\]
02

Calculate the final momentum of the ship

As the cruise ship comes to a stop, its final velocity is 0. Therefore, the final momentum (pf) is: \[pf = m \times v_f\] \[pf = (1.00 \times 10^{7} \mathrm{kg}) \times (0 \mathrm{m}/\mathrm{s})\] \[pf = 0 \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}\]
03

Calculate the change in momentum

Now, let's calculate the change in momentum (Δp) by subtracting the final momentum from the initial momentum: \[Δp = p_f - p_i\] Substitute the values of the initial and final momentum: \[Δp = 0 \mathrm{kg} \cdot \mathrm{m}/\mathrm{s} - 7.50 \times 10^6 \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}\] \[Δp = - 7.50 \times 10^6 \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}\]
04

Calculate the time to bring the ship to rest

To find the time it took to stop the ship, we can use the equation for acceleration. Since we know the initial velocity (v_i), the final velocity (v_f), and the distance (d) the ship traveled: \[v_f^2 = v_i^2 + 2ad\] We can find the acceleration(a) and then use it to find the time(t): \[a = \frac{v_f^2 - v_i^2}{2d}\] Substitute the values: \[a = \frac{(0 \mathrm{m}/\mathrm{s})^2 - (0.750 \mathrm{m}/\mathrm{s})^2}{2 \times 6.00 \mathrm{m}}\] Calculating the value of acceleration(a): \[a \approx - 0.09375 \mathrm{m}/\mathrm{s}^2\] Now, using the acceleration and initial velocity, we can find the time (t): \[t = \frac{v_f - v_i}{a}\] Substitute the values: \[t = \frac{0 \mathrm{m}/\mathrm{s} - 0.750 \mathrm{m}/\mathrm{s}}{- 0.09375 \mathrm{m}/\mathrm{s}^2}\] Calculating the value of time(t): \[t \approx 8.00 \mathrm{s}\]
05

Calculate the average force

Now that we know the change in momentum and the time, we can calculate the average force exerted on the pier using the concept of impulse (I = Δp = F × t): \[F = \frac{Δp}{t}\] Substitute the values of the change in momentum and time: \[F = \frac{- 7.50 \times 10^6 \mathrm{kg} \cdot \mathrm{m}/\mathrm{s}}{8.00 \mathrm{s}}\] Calculating the average force: \[F \approx - 9.375 \times 10^5 \mathrm{N}\] Since force is a vector, the negative sign indicates that the force exerted on the pier is in the opposite direction to the initial velocity of the cruise ship. So, the average force exerted on the pier is approximately \(9.375 \times 10^5 \mathrm{N}\) in the opposite direction to the initial motion of the ship.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Momentum Calculation
Momentum is a key concept in physics that involves understanding the "oomph" that an object possesses due to its motion. It’s calculated by multiplying the mass of the object by its velocity. For our cruise ship example, the mass is a whopping \( 1.00 \times 10^{7} \) kg, and its velocity just before crashing is \( 0.750 \) m/s.
Using the formula for momentum \( p = m \times v \), we plugged these values in and found that the initial momentum was \( 7.50 \times 10^6 \text{ kg} \cdot \text{m/s} \). But what happens when the cruise ship stops? The final momentum is zero because the final velocity is zero. Momentum helps us understand how difficult it is to either bring something in motion to a stop or start something at rest to move.
  • Momentum is a vector quantity, meaning it has both magnitude and direction.
  • Although the ship eventually stops, the initial momentum is not lost; rather, it is transferred elsewhere, in this case, to the pier.
Average Force
To understand the average force involved in bringing the cruise ship to a halt, we have to look at the concept of impulse. According to physics, impulse is equal to the change in momentum. We calculated earlier that the change in momentum (\( \Delta p \)) for the ship was \( -7.50 \times 10^6 \text{ kg} \cdot \text{m/s} \).
Impulse also equals the product of average force and time (\( F \times t \)), so we rearrange this to solve for the force: \( F = \frac{\Delta p}{t} \). By substituting the values for \( \Delta p \) and the time taken to stop (8.00 seconds), we find that the average force on the pier is approximately \( 9.375 \times 10^5 \text{ N} \).
  • Remember that force is a vector quantity, which means its direction matters. The negative sign in our force calculation indicates the direction is opposite to the ship's initial movement.
  • This force is exerted by the ship on the pier, causing damage as it comes to a stop.
Constant Acceleration
In our scenario, the cruise ship comes to a stop with constant acceleration over a known distance. This implies that the acceleration wasn't changing; it remained steady as the ship was brought to a halt over 6 meters.
We used the equation \( v_f^2 = v_i^2 + 2ad \) to determine this constant acceleration. By plugging in the initial speed, final speed (zero, since the ship stops), and the distance, we found that the acceleration was \( -0.09375 \text{ m/s}^2 \).
  • The negative sign indicates that this is a deceleration – a reduction in speed.
  • Constant acceleration means that the force bringing the ship to rest was unchanging throughout the entire process.

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Most popular questions from this chapter

You are coasting on your 10-kg bicycle at 15 m/s and a 5.0-g bug splatters on your helmet. The bug was initially moving at \(2.0 \mathrm{m} / \mathrm{s}\) in the same direction as you. If your mass is \(60 \mathrm{kg},\) (a) what is the initial momentum of you plus your bicycle? (b) What is the initial momentum of the bug? (c) What is your change in velocity due to the collision with the bug? (d) What would the change in velocity have been if the bug were traveling in the opposite direction?

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