Skip to main content
Ch 03: Motion in Two or Three Dimensions
Young & Freedman Calc - University Physics 15th Edition
Young & Freedman Calc15th EditionUniversity PhysicsISBN: 9780135159552Non è quello che usi tu?Cambia libro di testo
Capitolo 3, Problema 41b

A river flows due south with a speed of 2.0 m/s. You steer a motorboat across the river; your velocity relative to the water is 4.2 m/s due east. The river is 500 m wide. How much time is required to cross the river?

Guida verificata passo dopo passo
1
Identify the components of the boat's velocity. The boat's velocity relative to the water is 4.2 m/s due east, which is perpendicular to the river's flow.
Recognize that the width of the river is the distance the boat needs to travel across, which is 500 m.
Use the formula for time, \( t = \frac{d}{v} \), where \( d \) is the distance across the river (500 m) and \( v \) is the velocity of the boat relative to the water (4.2 m/s).
Substitute the values into the formula: \( t = \frac{500 \text{ m}}{4.2 \text{ m/s}} \).
Calculate the time required to cross the river using the formula from the previous step.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
3m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Relative Velocity

Relative velocity is the velocity of an object as observed from a particular frame of reference. In this problem, the boat's velocity relative to the water is given as 4.2 m/s due east, while the river flows south at 2.0 m/s. Understanding how these velocities combine is crucial for determining the boat's actual path and speed across the river.
Video consigliato:
Percorso guidato
04:27
Intro to Relative Motion (Relative Velocity)

Vector Components

Vector components are the projections of a vector along the axes of a coordinate system. Here, the boat's velocity can be split into eastward and southward components. The eastward component is 4.2 m/s, and the southward component is due to the river's flow at 2.0 m/s. Calculating these components helps in determining the resultant velocity and the time to cross the river.
Video consigliato:
Percorso guidato
07:30
Vector Addition By Components

Time Calculation

Time calculation involves determining how long it takes for an object to travel a certain distance at a given speed. In this scenario, the width of the river is 500 m, and the boat's effective velocity across the river is 4.2 m/s. Using the formula time = distance/speed, we can calculate the time required to cross the river, focusing on the eastward component of the boat's velocity.
Video consigliato:
Percorso guidato
04:43
Calculating Displacement from Velocity-Time Graphs
Pratica correlata
Domanda del libro di testo

An airplane pilot wishes to fly due west. A wind of 80.0 km/h (about 50 mi/h) is blowing toward the south. What is the speed of the plane over the ground? Draw a vector diagram.

1789
views
Domanda del libro di testo

An airplane pilot wishes to fly due west. A wind of 80.0 km/h (about 50 mi/h) is blowing toward the south. If the airspeed of the plane (its speed in still air) is 320.0 km/h (about 200 mi/h), in which direction should the pilot head?

3640
views
1
rank
Domanda del libro di testo

The nose of an ultralight plane is pointed due south, and its airspeed indicator shows 35 m/s35\(\text{ m/s}\). The plane is in a 10 m/s10\(\text{ m/s}\) wind blowing toward the southwest relative to the earth. Let xx be east and yy be north, and find the components of v→P/E\(\overrightarrow{v}\)_{P/E} .

1914
views
Domanda del libro di testo

The nose of an ultralight plane is pointed due south, and its airspeed indicator shows 35 m/s35\(\text{ m/s}\). The plane is in a 10 m/s10\(\text{ m/s}\) wind blowing toward the southwest relative to the earth. In a vector-addition diagram, show the relationship of v→P/E\(\overrightarrow{v}\)_{P/E} (the velocity of the plane relative to the earth) to the two given vectors.

2699
views
Domanda del libro di testo

A river flows due south with a speed of 2.0 m/s. You steer a motorboat across the river; your velocity relative to the water is 4.2 m/s due east. The river is 500 m wide. What is your velocity (magnitude and direction) relative to the earth?

2737
views