After the astronaut applies the force to the keyboard, the astronaut

Which of the following does NOT create a mechanical wave? Text to speech

Cerrena [4.2K]

Light coming through a window!!

4 0

3 years ago

An antelope moving with constant acceleration covers the distance 68.0 m between two points in time 7.50 s. Its speed as it pass

Darya [45]

Answer:

A)The speed of the antelope at the first point is 2.43 m/s.

B) The acceleration of the antelope is 1.77 m/s²

Explanation:

The equations of the position and velocity of the antelope is given by the following expressions:

x = x0 + v0 · t + 1/2 · a ·t²

v = v0 + a · t

Where:

x = position of the antelope at time t

x0 = initial position

v0 = initial velocity

t = time

a = acceleration

v = velocity at time t

A) Let´s place the center of the frame of reference at the first point. The equation of position at t = 7.50 s will be:

x = x0 + v0 · t + 1/2 · a ·t²

68.0 m = 0 m + v0 · 7.50 s + 1/2 · a · (7.50 s)²

We also know that at the second point the velocity is 15.7 m/s. Then at t = 7.50 the velocity will be 15.7 m/s.

v = v0 + a · t

15.7 m/s = v0 + a · 7.50 s

We can solve this equation for "a" and replace it in the equation of height to obtain "v0". Then:

a = (15.7 m/s - v0) / 7.50 s

Replacing it in the equation for position:

68.0 m = 0 m + v0 · 7.50 s + 1/2 · a · (7.50 s)²

68.0 m = v0 · 7.50 s + 1/2 · (15.7 m/s - v0) / 7.50 s · (7.50 s)²

68.0 m = v0 · 7.50 s + 7.85 m/s · 7.50 s - 3.75 s · v0

68.0 m - 7.85 m/s · 7.50 s = 3.75 s · v0

(68.0 m - 7.85 m/s · 7.50 s) / 3.75 s = v0

v0 = 2.43 m/s

The speed of the antelope at the first point is 2.43 m/s.

B) The acceleration of the antelope will be:

a = (15.7 m/s - v0) / 7.50 s

a = (15.7 m/s - 2.43 m/s) / 7.50 s

a = 1.77 m/s²

The acceleration of the antelope is 1.77 m/s²

5 0

3 years ago

"a horn emits a frequency of 1000 HZ. A 14 m/s wind is blowing toward a listener. What is the frequency of the sound heard by th

Semenov [28]

Answer:

$f_L = 1000 Hz$

Explanation:

given,

speed of wind, = 14 m/s

frequency of horn,f_s = 1000 Hz

speed of sound,V = 344 m/s

frequency heard by the listener

using Doppler effect

$f_L = \dfrac{v+v_L}{v+v_s}f_s$

f_L is the frequency of the sound heard by the listener

f_s is the frequency of sound emitted by the listener

V is the speed of sound

v_L is the speed of listener

v_s is the speed of source

now,

considering the frame of reference in which wind is at rest now, both listener and the source will be moving at 14 m/s

$f_L = \dfrac{v+14}{v+14}\times 1000$

now on solving we will get

$f_L = 1000 Hz$

hence, the frequency heard by the listener is equal to 1000 Hz

7 0

3 years ago

Does anyone know 19 and 20 ??

harina [27]

B I think for 19 and D for 20

4 0

3 years ago

Under what conditions does q, the heat evolved or absorbed by the system in a physical or chemical process, equal the change in

Paladinen [302]

Answer: When $w=-P\Delta V$

Explanation:

According to first law of thermodynamics, energy can neither be created nor be destroyed. It can only be transformed from one form to another.

$\Delta H=\Delta E+P\Delta V$

$\Delta E=q+w$

$\Delta H$ = change in enthalpy

P = pressure

$\Delta V$ = change in volume

$\Delta E$ =Change in internal energy

q = heat absorbed or released

w = work done on or by the system

$\Delta H=q+w+P\Delta V$

Thus for $\Delta E=q+w$ , $w=-P\Delta V$

The heat evolved or absorbed by the system in a physical or chemical process, equal the change in enthalpy of the system when $w=-P\Delta V$

8 0

4 years ago