1. starting from the center of town, a car travels east for 80.0 km and then turns due south for another 192 km, at which point it runs out of gas. Determine the displacement of the stopped car from the center of town and it direction

2. A little turtle is placed at of an xy-grid drawn on a large sheet of paper. Each grid box is 1.0cm by 1.0cm. The turtle walks around for a while and finally ends up at point (24, 10), that is, 24 boxes along the x-axis and 10 boxes along the y-axis. Determine the displacement of the turtle from the origin at the point and its direction.
3. A bug starts at point A, crawl 8.0cm east, than 5.0cm south, 3.0cm west and 4 0cm north to point B. (a) how far north and east is B from A (b) find the displacement and direction from A to B both graphically and algebraically.
4. Find the scaler x- and y-components of the following displacements in the xy plane: (a) 300cm at 127° and (b) 500cm at 220°
5. Two forces act on a point objects as follows: 100N at 170 0° and 100N at 50.0°. Find the resultant
6. Starting at the origin of coordinates, the following displacements are made in the xy-plane (that is, the displacement are coplanar): 60mm in the +y-direction, 30mm in the -x-direction, 40mm at 150°, and 50mm at 240°. Find the resultant displacement and direction both graphically and algebraically

1 answer

Let's go through these problems step by step.

1. Displacement of the Car

The car travels 80.0 km east and then 192 km south. We can represent these movements with vector components.

  • East (x-direction): \( x_1 = 80.0 , \text{km} \)
  • South (y-direction): \( y_1 = -192 , \text{km} \)

To find the resultant displacement \( R \), we can use the Pythagorean theorem: \[ R = \sqrt{x_1^2 + y_1^2} = \sqrt{(80.0)^2 + (-192)^2} \] \[ R = \sqrt{6400 + 36864} = \sqrt{43264} \approx 207.93 , \text{km} \]

To find the direction (angle \( \theta \)) with respect to the east (x-axis): \[ \theta = \tan^{-1} \left( \frac{y_1}{x_1} \right) = \tan^{-1} \left( \frac{-192}{80} \right) \approx -67.38^\circ \] This angle is measured from the positive x-axis (east) toward the negative y-axis (south).

Summary for Car

  • Displacement: \( \approx 207.93 , \text{km} \)
  • Direction: \( 67.4^\circ \) south of east.

2. Displacement of the Turtle

The turtle ends up at point \( (24, 10) \).

The displacement from the origin (0,0) to (24, 10) can be found using: \[ R = \sqrt{x^2 + y^2} = \sqrt{(24)^2 + (10)^2} \] \[ R = \sqrt{576 + 100} = \sqrt{676} = 26 , \text{cm} \]

To find the direction: \[ \theta = \tan^{-1}\left( \frac{y}{x} \right) = \tan^{-1}\left( \frac{10}{24} \right) \approx 22.62^\circ \]

Summary for Turtle

  • Displacement: \( 26 , \text{cm} \)
  • Direction: \( 22.6^\circ \) above the positive x-axis.

3. Displacement of the Bug

The bug's movements can be summarized as follows:

  • East: \( 8.0 , \text{cm} \)
  • South: \( 5.0 , \text{cm} \)
  • West: \( 3.0 , \text{cm} \)
  • North: \( 4.0 , \text{cm} \)

Net displacements:

  • North-South: \( 4.0 - 5.0 = -1.0 , \text{cm} \) (1 cm south)
  • East-West: \( 8.0 - 3.0 = 5.0 , \text{cm} \) (5 cm east)

(a) From point A to point B:

  • North: \( -1.0 , \text{cm} \) (1 cm south)
  • East: \( 5.0 , \text{cm} \) (5 cm east)

(b) Find the displacement \( R \): \[ R = \sqrt{(5)^2 + (-1)^2} = \sqrt{25 + 1} = \sqrt{26} \approx 5.10 , \text{cm} \]

Direction: \[ \theta = \tan^{-1} \left( \frac{-1}{5} \right) \approx -11.31^\circ \]

Summary for Bug

  • North/South: \( 1.0 , \text{cm} \) south
  • East/West: \( 5.0 , \text{cm} \) east
  • Displacement: \( \approx 5.10 , \text{cm} \)
  • Direction: \( 11.3^\circ \) south of east.

4. Scalar Components of Displacements

For each angle, we will decompose the vector into x and y components using:

\[ x = r \cos(\theta), \quad y = r \sin(\theta) \]

(a) For \( 300, \text{cm} , \text{at} , 127^\circ \): \[ x = 300 \cos(127^\circ) \approx -180.95 , \text{cm} \] \[ y = 300 \sin(127^\circ) \approx 227.76 , \text{cm} \]

(b) For \( 500, \text{cm} , \text{at} , 220^\circ \): \[ x = 500 \cos(220^\circ) \approx -469.85 , \text{cm} \] \[ y = 500 \sin(220^\circ) \approx -125.00 , \text{cm} \]

Summary for Components

(a) \( x \approx -180.95 , \text{cm}, , y \approx 227.76 , \text{cm} \) (b) \( x \approx -469.85 , \text{cm}, , y \approx -125.00 , \text{cm} \)


5. Resultant Forces

Two forces given:

  • \( F_1 = 100 , \text{N} \) at \( 170^\circ \)
  • \( F_2 = 100 , \text{N} \) at \( 50^\circ \)

Components: \[ F_{1x} = 100 \cos(170^\circ) = -96.19 , \text{N}, \quad F_{1y} = 100 \sin(170^\circ) = 17.36 , \text{N} \] \[ F_{2x} = 100 \cos(50^\circ) \approx 64.28 , \text{N}, \quad F_{2y} = 100 \sin(50^\circ) \approx 76.94 , \text{N} \]

Resultant components: \[ R_x = F_{1x} + F_{2x} \approx -96.19 + 64.28 \approx -31.91 , \text{N} \] \[ R_y = F_{1y} + F_{2y} \approx 17.36 + 76.94 \approx 94.30 , \text{N} \]

Magnitude: \[ R = \sqrt{R_x^2 + R_y^2} \approx \sqrt{(-31.91)^2 + (94.30)^2} \approx 98.87 , \text{N} \]

Direction: \[ \theta = \tan^{-1}\left( \frac{R_y}{R_x} \right) = \tan^{-1}\left( \frac{94.30}{-31.91} \right) \approx 112.6^\circ \]

Summary for Forces

  • Resultant Force: \( \approx 98.87 , \text{N} \)
  • Direction: \( 112.6^\circ \) from the positive x-axis.

6. Resultant Displacement

Starting at the origin and given the movements:

  1. \( (0, 60) \)
  2. \( (-30, 0) \)
  3. Calculate from angle \( 150^\circ\): \[ R_3 = 40(\cos(150^\circ), \sin(150^\circ)) \approx (-20, 20) \]
  4. Calculate from angle \( 240^\circ\): \[ R_4 = 50(\cos(240^\circ), \sin(240^\circ)) \approx (25(-0.5), 25(-\sqrt{3}/2)) \approx (-25, -21.65) \]

Now summing these vectors:

  • \( x_{\text{total}} = 0 + (-30) + (-20) + (-25) = -75 \)
  • \( y_{\text{total}} = 60 + 0 + 20 + (-21.65) \approx 58.35 \)

Resultant displacement: \[ R = \sqrt{(-75)^2 + (58.35)^2} \approx 92.93 , \text{mm} \] Direction: \[ \theta = \tan^{-1}\left( \frac{58.35}{-75} \right) \approx 143.59^\circ \]

Summary for Resultants

  • Resultant Displacement: \( \approx 92.93 , \text{mm} \)
  • Direction: \( 143.6^\circ \) from the positive x-axis.