Waves that move the particles of the medium parallel to the direction in which the waves are traveling are called?

An object moves in a circular path at a constant speed. What is the relationship between the directions of the object's velocity

Reil [10]

Answer:

b

Explanation:

When an object is in circular motion, the direction of velocity is in the direction of tangent to the circle and acceleration is always directed towards the radial direction. This means that velocity is always perpendicular to acceleration of the object.

Hence option (b)-The velocity and acceleration vectors are perpendicular is correct.

3 0

3 years ago

The following questions present a twist on the scenario above to test your understanding. Suppose another stone is thrown horizo

Ipatiy [6.2K]

The first part of the text is missing, you can find on google:

"A ball is thrown horizontally from the roof of a building 45 m. If it strikes the ground 56 m away, find the following values."

Let's now solve the different parts.

(a) 3.03 s

The time of flight can be found by analyzing the vertical motion only. The vertical displacement at time t is given by

$y(t) = h -\frac{1}{2}gt^2$

where

h = 45 m is the initial height

g = 9.8 m/s^2 is the acceleration of gravity

When y=0, the ball reaches the ground, so the time taken for this to happen can be found by substituting y=0 and solving for the time:

$0=h-\frac{1}{2}gt^2\\t=\sqrt{\frac{2h}{g}}=\sqrt{\frac{2(45)}{9.8}}=3.03 s$

(b) 18.5 m/s

For this part, we need to analyze the horizontal motion only, which is a uniform motion at constant speed.

The horizontal position is given by

$x=v_x t$

where

$v_x$ is the horizontal speed, which is constant

t is the time

At t = 3.03 s (time of flight), we know that the horizontal position is x = 56 m. By substituting these numbers and solving for vx, we find the horizontal speed:

$v_x = \frac{x}{t}=\frac{56}{3.03}=18.5 m/s$

The ball was thrown horizontally: this means that its initial vertical speed was zero, so 18.5 m/s was also its initial overall speed.

(c) 35.0 m/s at 58.1 degrees below the horizontal

At the impact, we know that the horizontal speed is still the same:

$v_x = 18.5 m/s$

we need to find the vertical velocity. This can be done by using the equation

$v_y = u_y -gt$

where

$u_y =0$ is the initial vertical velocity

g is the acceleration of gravity

t is the time

Substituting t = 3.03 s, we find the vertical velocity at the time of impact:

$v_y = -(9.8)(3.03)=-29.7 m/s$

So the magnitude of the velocity at the impact (so, the speed at the impact) is

$v=\sqrt{v_x^2+v_y^2}=\sqrt{18.5^2+(-29.7)^2}=35.0 m/s$

The angle instead can be found as:

$\theta=tan^{-1}(\frac{v_y}{v_x})=tan^{-1}(\frac{-29.7}{18.5})=-58.1^{\circ}$

so, 58.1 degrees below the horizontal.

4 0

3 years ago

The spin-drier of a washing machine revolving at 900.RPM slows down uniformly to 300.RPM while making 60. revolutions. Find the

jeyben [28]

<h2>Answer:</h2>

<u>Acceleration is </u><u>-10.57 rad/s² </u>

<u>Time is </u><u>6 seconds</u>

<h2>Explanation:</h2><h3>a) </h3>

u=900rpm= 94.248 rad/s

v =300rpm= 31.416 rad/s

s=60 revolutions= 377 rad

v²= u²+ 2as

31.416² = 94.248²+ 2 * a * 377

a = v²-u² / 2s

a= -10.57 rad/s²

Using 1st equation of motion

v-u/a = t

Putting the values

t = (31.4 - 94.2)/-10.57

t = 6 seconds

3 0

3 years ago

The power of a red laser (λ = 630 nm) is 3.25 watts (abbreviated w, where 1 w = 1 j/s). how many photons per second does the las

lisabon 2012 [21]

The energy delivered by the laser in 1 second is $E_t=Pt = (3.25 W)(1.0 s)=3.25 J$
In order to find how many photons correspond to this energy, we must calculate the energy of a single photon.
Calling h the Planck constant, c the speed of light and $\lambda=630 nm=630 \cdot 10^{-9}m$ the wavelength of the light, the energy of a single photon is given by
$E=h \frac{c}{\lambda}=(6.6 \cdot 10^{-34} Js) \frac{3 \cdot 10^8 m/s}{630 \cdot 10^{-9}m}= 3.1 \cdot 10^{-19} J$

So, the number of photons emitted by the laser in 1 second is equal to the total energy delivered by the laser divided by the energy of a single photon:
$N= \frac{E_t}{E}= \frac{3.25 J}{3.1 \cdot 10^{-19} J} =1.0 \cdot 10^{19}$ photons

5 0

3 years ago

Physics!!! please help D:

Ugo [173]

Answer: A

Explanation: isotopes of the same thing element have the same number of protons in the nucleus but differ in the number of neutrons.

6 0

3 years ago