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4 years ago

Electromagnetic waves and sound waves can have the same frequency. what is the wavelength of a 1.10 khz electromagnetic wave

1 answer:

7 0

The wavelength of an electromagnetic wave is given by
$\lambda = \frac{c}{f}$
where $c=3 \cdot 10^8 m/s$ is the speed of light and $f=1.10 kHz = 1100 Hz$ is the frequency. Substituting the numbers, we find
$\lambda = \frac{3 \cdot 10^8 m/s}{1100 Hz}=2.72 \cdot 10^5 m=272 km$
So, the wave in the problem has a wavelength of 272 km.

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How much work would be needed to lift the ball from the 2-m shelf to the 5-m shelf, and how much potential energy would it have

Stells [14]

Answer:

a) 2.94 N

b) 4.90 N

Explanation:

Let us assume that the weight of the ball is 0.98 N

Solution:

a) An object’s gravitational potential energy depends on two factors which are height and its weight (or mass). The equation for gravitational potential energy (PE) is given as:

Potential energy = weight (w) * height (h)

PE = wh

Potential energy at 2 m shelf = weight * height = 0.98 N * 2 m = 1.96 N

Potential energy at 5 m shelf = weight * height = 0.98 N * 5 m = 4.90 N

The work needed to lift the ball from the 2-m shelf to the 5-m shelf = Potential energy at 5 m shelf - Potential energy at 2 m shelf

The work needed to lift the ball from the 2-m shelf to the 5-m shelf = 4.90 N - 1.96 N = 2.94 N

b) Potential energy at 5 m shelf = weight * height = 0.98 N * 5 m = 4.90 N

6 0

3 years ago

What is the power of a kitchen blender if it can perform 2000 joules of work in 5 seconds ?

soldier1979 [14.2K]

Power = (work done) / (time to do the work)

Power = (2000 J) / (5 sec)

<em>Power = 400 watts</em>

7 0

3 years ago

Hurry i have until 4 to turn in

Mariana [72]

Answer:

9miles average speed and 23 seconds

7 0

3 years ago

A car is traveling north at 17.7m/s After 12 s its velocity is 14.1m/s in the same direction. Find the magnitude and direction o

dem82 [27]

Answer:

Option B

0.3 m/s2 South

Explanation:

Acceleration, $a=\frac {v-u}{t}$ where v and u are final and initial velocities respectively, t is the time taken

Substituting 14.1 m/s for v, 17.7 m/s for u and 12 s for t then

$a=\frac {14.1 m/s- 17.7 m/s}{12}=-0.3 m/s^{2}$

Since this is negative acceleration, it's direction is opposite hence 0.3 m/s2 South

7 0

3 years ago

deals with the concepts that are important in this problem. A grasshopper makes four jumps. The displacement vectors are (1) 31.

Troyanec [42]

(a) 46.6 cm

To calculate the total displacement, we need to resolve each vector along the x- and y- direction.

In the following, we take:

- East as positive x-direction, West as negative x-direction

- North as positive y-direction, South as negative y-direction

Vector A:

$A_x = -31.0 cm\\A_y = 0$

Vector B:

$B_x = -(32.0 cm) cos 34.0^{\circ}=-25.6 cm\\B_y = -(32.0 cm) sin 34.0^{\circ} = -17.9 cm$

Vector C:

$C_x = (16.0 cm)cos 57.0^{\circ} =8.7 cm\\C_y = -(16.0 cm)sin 57.0^{\circ} =-13.4 cm$

Vector D:

$D_x = (16.0 cm) cos 75.0^{\circ} =4.1 cm\\D_y = (16.0 cm) sin 75.0^{\circ} =15.5 cm$

So the components of the total displacement are:

$R_x = -31.0 cm - 25.6 cm +8.7 cm +4.1 cm =-43.8 cm\\R_y = 0-17.9 cm -13.4 cm +15.5 cm =-15.8 cm$

So the magnitude of the total displacement is:

$R=\sqrt{R_x^2 + R_y^2}=\sqrt{(-43.8 cm)^2+(-15.8 cm)^2}=46.6 cm$

(b) 19.8 degrees south of west

First of all, let's notice that:

- both components x and y of the total displacement are negative --> this means that the direction of the displacement is south of west

This means that the angle will be given by

$\theta = tan^{-1} (\frac{R_y}{R_x})$

where we have

$R_x = -43.8 cm\\R_y = -15.8 cm$

Substituting, we find

$\theta = tan^{-1} (\frac{-15.8 cm}{43.8 cm})=19.8^{\circ}$

and this angle is south of west.

7 0

3 years ago