/*! 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 61 A Toyota Prius driving north at ... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

A Toyota Prius driving north at 65 \(\mathrm{mph}\) and a \(\mathrm{VW}\) Passat driving south at 42 \(\mathrm{mph}\) are on the same road heading toward each other (but in different lanes). What is the velocity of each car relative to the other (a) when they are 250 \(\mathrm{ft}\) apart, just before they meet, and (b) when they are 525 \(\mathrm{ft}\) apart, after they have passed each other?

Short Answer

Expert verified
Relative velocity is 107 mph before meeting and remains 107 mph after passing.

Step by step solution

01

Understanding relative velocity

Relative velocity is the velocity of one object as observed from another moving object. In this case, we need to find the relative velocity of the Prius with respect to the Passat, and vice versa.
02

Determine combined velocity

When two objects are moving towards or away from each other, the relative velocity is equal to the sum of their individual velocities if directions are opposite, or the difference if directions are the same. Since the Prius is going north and the Passat is going south, their velocities add up. The combined velocity: \[65\,\mathrm{mph} + 42\,\mathrm{mph} = 107 \,\mathrm{mph}\]
03

Velocity of Prius relative to Passat (Part a)

Since the Prius and Passat are approaching each other from opposite directions, the relative velocity of the Prius as observed from the Passat is 107 mph towards the Passat. However, relative velocity does not change with distance until they have passed each other.
04

Velocity of Passat relative to Prius (Part b)

Likewise, before and after meeting, the relative velocity of the Passat as observed from the Prius is 107 mph towards the Prius. Once they pass each other, the relative velocity doesn't change in magnitude but it continues in the opposite direction.
05

Conclusion about distance effect on relative velocity

Just before meeting and after passing, despite the change in distance (250 ft and 525 ft), the relative velocity between moving objects remains the same unless there's a change in their actual velocities. The scenario assumes they maintain constant speeds.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Motion
Motion describes the change in position of objects over time. Every moving object experiences some form of motion, whether linear, rotational, or oscillatory. In physics, motion is usually considered with respect to a reference point. For example, a car driving down the road appears to be moving forward from the perspective of a stationary observer on the sidewalk. However, that same car might seem completely still to a passenger.
In our case, both Prius and Passat are in motion, traveling towards one another. The state of motion is described relative to each other, which leads us to the concept of relative velocity. Distances between the cars change depending on their directions and speeds, which will determine the time it takes for them to meet or pass each other completely. Therefore, motion and its comprehension are fundamental to understanding the observed relative velocity.
Velocity
Velocity is a vector that indicates both the speed and direction of an object's motion. Speed is a scalar quantity, focusing only on how fast an object is moving, with no concern for direction, whereas velocity takes both into consideration.
In this context, the velocity of the Toyota Prius and the VW Passat needs not only to consider their speeds—65 mph and 42 mph, respectively—but also the directions they are traveling. The Prius heading north and the Passat heading south tells us they are moving in opposite directions. The velocity can be positive in one direction and negative in the other, depending on the chosen frame of reference. This variance in direction is essential for calculating relative velocity.
Vectors
Vectors are quantities defined by both magnitude and direction, and they play a crucial role in understanding motion and velocity. Examples include displacement, velocity, acceleration, and force. They are usually represented graphically with arrows, where the length of the arrow reflects the vector's magnitude, and its direction shows the vector's direction.
In analyzing the problem, we use vector addition to calculate relative velocity. While the Prius moves north at 65 mph and the Passat moves south at 42 mph, their velocities can be represented as vectors pointing in opposite directions. By adding these vectors (since they are in opposite directions), we arrive at a combined relative velocity of 107 mph. This result helps us visualize how vectors simplify solving such problems and clarify the combined motion of the two cars.
Distance
Distance in physics represents how far apart objects are. It is a scalar quantity, only considering the magnitude without any direction. In the provided problem, the distances of 250 feet and 525 feet were given to describe the intervals at which the velocities are questioned.
It is important to note that while distance changes as the cars move, relative velocity remains constant unless there are speed changes. This particular problem assumes constant speeds, so regardless of the distance between the Prius and the Passat, their relative velocity does not vary. Such an understanding underscores the independence of relative velocity from distance, provided that the speeds of the observed objects remain unchanged.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

The freeway blues! When you normally drive the freeway between Sacramento and San Francisco at an average speed of \(105 \mathrm{km} / \mathrm{hr}(65 \mathrm{mph}),\) the trip takes 1.0 \(\mathrm{hr}\) and 20 min. On a Friday afternoon, however, heavy traffic slows you down to an average of 70 \(\mathrm{km} / \mathrm{hr}(43 \mathrm{mph})\) for the same distance. How much longer does the trip take on Friday than on the other days?

Animal motion. Cheetahs, the fastest of the great cats, can reach 45 mph in 2.0 starting from rest. Assuming that they have constant acceleration throughout that time, find (a) their acceleration (in \(\mathrm{ft} / \mathrm{s}^{2}\) and \(\mathrm{m} / \mathrm{s}^{2}\) and (b) the distance (in \(\mathrm{m}\) and ft) they travel during that time.

A 0.525 kg ball starts from rest and rolls down a hill with uniform acceleration, traveling 150 m during the second 10.0 \(\mathrm{s}\) of its motion. How far did it roll during the first 5.0 s of motion?

A speedy basketball point guard is 5 ft 10 inches tall; the center on the same team is 7 ft 2 inches tall. Assuming their bodies are similarly proportioned, if the point guard weighs 175 lb, what would you expect the center to weigh?

That's a lot of hot air! A hot-air balloonist, rising vertically with a constant speed of 5.00 \(\mathrm{m} / \mathrm{s}\) releases a sandbag at the instant the balloon is 40.0 \(\mathrm{m}\) above the ground. (See Figure \(2.52 . )\) After it is released, the sandbag encounters no appreciable air drag. (a) Compute the position and velocity of the sandbag at 0.250 s and 1.00 s after its release. (b) How many seconds after its release will the bag strike the ground? (c) How fast is it moving as it strikes the ground? (d) What is the greatest height above the ground that the sandbag reaches? (e) Sketch graphs of this bag's acceleration, velocity, and vertical position as functions of time.

See all solutions

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.