What is the speed of a wave that has a frequency of 25Hz and a wavelength of 3m

A double insulated drill ____. A. has two ground wires to insure proper grounding B. generally has a plastic case with the elect

Len [333]

Answer:

Option B is correct.

A double insulated drill generally has a plastic case with the electrical connections and motor insulated within the tool

Explanation:

A double insulated drill's design in real life has plastic casing as the insulator & it wouldn't be a drill without its motor now, would it!?

8 0

3 years ago

The photographer realizes that with the lens she is currently using, she can't fit the entire landscape she is trying to photogr

dexar [7]

She should use shorter focal length to fit the entire landscape which she is trying to photograph into her picture.

What is focal length?

The focal length is a measure of how strongly the system converges or diverges light.

A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light.

For a standard rectilinear lens,

FOV = 2 arctan (x/2f)

FOV ∝ 1 / f

where x is the diagonal of the film.

Focal length (f) and field of view (FOV) of a lens are inversely proportional.

From the equation we can say that,

A shorter focal length gives you a wide angle of view which allows more view to fit in the frame.

Hence,

She should use shorter focal length to fit the entire landscape which she is trying to photograph into her picture.

Learn more about focal length here

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5 0

2 years ago

Will Mark Brainliest if Correct PLZ!!!!! A bullet is shot at some angle above the horizontal at an initial velocity of 87m/s on

qaws [65]

Answer:

≅50°

Explanation:

We have a bullet flying through the air with only gravity pulling it down, so let's use one of our kinematic equations:

Δx=V₀t+at²/2

And since we're using Δx, V₀ should really be the initial velocity in the x-direction. So:

Δx=(V₀cosθ)t+at²/2

Now luckily we are given everything we need to solve (or you found the info before posting here):

Δx=760 m
V₀=87 m/s
t=13.6 s
a=g=-9.8 m/s²; however, at 760 m, the acceleration of the bullet is 0 because it has already hit the ground at this point!

With that we can plug the values in to get:

$760=(87)(cos\theta )(13.6)+\frac{(0)(13.6^{2}) }{2}$

$760=(1183.2)(cos\theta)$

$cos\theta=\frac{760}{1183.2}$

$\theta=cos^{-1}(\frac{760}{1183.2})\approx50^{o}$

3 0

3 years ago

If eight water waves pass an ocean buoy each minute, and successive wave crests are 20 m apart, find the wave speed:____________

Llana [10]

Answer:

The wave speed is calculated below:

Explanation:

Given,

number of waves passed per minute = 8

time period = 1 minute = 60 s

distance between successive wave crests = 20 m

waves passing interval per second = $\frac{8}{60}$ $s^{-1}$

Now,

wave speed = 20 m × $\frac{8}{60}$ $s^{-1}$

= $\frac{8}3}$ m/s

= 2.67 m/s

Hence the wave speed is 2.67 m/s.

4 0

3 years ago

When the play button is pressed, a CD accelerates uniformly from rest to 450 rev/min in 3.0 revolutions. If the CD has a radius

Marina CMI [18]

To solve this problem it is necessary to apply the kinematic equations of angular motion.

Torque from the rotational movement is defined as

$\tau = I\alpha$

where

I = Moment of inertia $\rightarrow \frac{1}{2}mr^2$ For a disk

$\alpha =$ Angular acceleration

The angular acceleration at the same time can be defined as function of angular velocity and angular displacement (Without considering time) through the expression:

$2 \alpha \theta = \omega_f^2-\omega_i^2$

Where

$\omega_{f,i} =$ Final and Initial Angular velocity

$\alpha =$ Angular acceleration

$\theta =$ Angular displacement

Our values are given as

$\omega_i = 0 rad/s$

$\omega_f = 450rev/min (\frac{1min}{60s})(\frac{2\pi rad}{1rev})$

$\omega_f = 47.12rad/s$

$\theta = 3 rev (\frac{2\pi rad}{1rev}) \rightarrow 6\pi rad$

$r = 7cm = 7*10^{-2}m$

$m = 17g = 17*10^{-3}kg$

Using the expression of angular acceleration we can find the to then find the torque, that is,

$2\alpha\theta=\omega_f^2-\omega_i^2$

$\alpha=\frac{\omega_f^2-\omega_i^2}{2\theta}$

$\alpha = \frac{47.12^2-0^2}{2*6\pi}$

$\alpha = 58.89rad/s^2$

With the expression of the acceleration found it is now necessary to replace it on the torque equation and the respective moment of inertia for the disk, so

$\tau = I\alpha$

$\tau = (\frac{1}{2}mr^2)\alpha$

$\tau = (\frac{1}{2}(17*10^{-3})(7*10^{-2})^2)(58.89)$

$\tau = 0.00245N\cdot m \approx 2.45*10^{-3}N\cdot m$

Therefore the torque exerted on it is $2.45*10^{-3}N\cdot m$

3 0

3 years ago