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3 years ago

If a car travels 80 miles between 2 and 4 pm, then its velocity is close to 40 mph at 2 pm.

1 answer:

3 0

The answer should be false because it doesnt say if the car is traveling at constant speed. The cars speed can be various so that in total for 2 hours that it travels it passes 80 miles. If however it actually traveled at constant speed than the answer is true.

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Sound will travel slowest through which medium?

xxMikexx [17]

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3 years ago

Here's an interesting challenge you can give to a friend. Hold a $1 bill by the upper corner. Have a friend prepare to pinch the

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3 years ago

Read 2 more answers

A short-wave radio antenna is supported by two guy wires, 155 ft and 175 ft long. Each wire is attached to the top of the antenn

Vladimir79 [104]

Answer:

163.8 ft

Explanation:

In triangle ABD

$AB$ = 155 ft

$Cos63 = \frac{BD}{AB} = \frac{BD}{155}\\BD = 155 Cos63 \\BD = 70.4 ft$

$Sin63 = \frac{AD}{AB} = \frac{AD}{155} \\AD = 166 Sin63\\AD = 148 ft$

Using Pythagorean theorem in triangle ADC

$AC^{2} = AD^{2} + DC^{2} \\175^{2} = 148^{2} + DC^{2} \\DC = 93.4 ft$

$d$ = distance between the anchor points

distance between the anchor points is given as

$d = BD + CD = 70.4 + 93.4\\d = 163.8 ft$

5 0

3 years ago

Read 2 more answers

Suppose that a wind is blowing in the direction S45°E at a speed of 30 km/h. A pilot is steering a plane in the direction N60°E

Kay [80]

Answer:

The true course: $40.29^\circ$ north of east

The ground speed of the plane: 96.68 m/s

Explanation:

Given:

$V_w$ = velocity of wind = $30\ km/h\ S45^\circ E = (30\cos 45^\circ\ \hat{i}-30\sin 45^\circ\ \hat{j})\ km/h = (21.21\ \hat{i}-21.21\ \hat{j})\ km/h$

$V_p$ = velocity of plane in still air = $100\ km/h\ N60^\circ E = (100\cos 60^\circ\ \hat{i}+100\sin 60^\circ\ \hat{j})\ km/h = (50\ \hat{i}+86.60\ \hat{j})\ km/h$

Assume:

$V_r$ = resultant velocity of the plane

$\theta$ = direction of the plane with the east

Since the resultant is the vector addition of all the vectors. So, the resultant velocity of the plane will be the vector sum of the wind velocity and the plane velocity in still air.

$\therefore V_r = V_p+V_w\\\Rightarrow V_r = (50\ \hat{i}+86.60\ \hat{j})\ km/h+(21.21\ \hat{i}-21.21\ \hat{j})\ km/h\\\Rightarrow V_r = (71.21\ \hat{i}+65.39\ \hat{j})\ km/h$

Let us find the direction of this resultant velocity with respect to east direction:

$\theta = \tan^{-1}(\dfrac{65.39}{71.21})\\\Rightarrow \theta = 40.29^\circ$

This means the the true course of the plane is in the direction of $40.29^\circ$ north of east.

The ground speed will be the magnitude of the resultant velocity of the plane.

$\therefore Magnitude = \sqrt{71.21^2+65.39^2} = 96.68\ km/h$

Hence, the ground speed of the plane is 96.68 km/h.

5 0

3 years ago

The wavelength of a certain portion of an electromagnetic wave is 314 nm. what is its frequency and classification?

nadezda [96]

The frequency of the electromagnetic wave is 9.55 × 1014 Hz and it is classified as ultraviolet.

<h3>What is meant by electromagnetic waves?</h3>

Electromagnetic waves are forms of energy that are invisible and travel throughout the universe. However, some of the effects of this energy are visible. The light that we see is a component of the electromagnetic spectrum.

Electromagnetic waves, or EM waves, are produced by vibrations between an electric field and a magnetic field. In other words, electromagnetic waves are made up of oscillating magnetic and electric fields.

<h3>How do you calculate the speed of an electromagnetic wave?</h3>

The wavelength and frequency of any periodic wave are used to calculate its speed. v = λf.

In free space, the speed of any electromagnetic wave is equal to the speed of light, c = 3 $*$ 108 m/s.

The frequency of the electromagnetic wave is 9.55 × 1014 Hz and it is classified as ultraviolet.

To learn more about electromagnetic wave refer to:

brainly.com/question/25847009

#SPJ4

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2 years ago