True or False!?

The concept of critical density is just like the idea of escape velocity for a projectile launched from the earth. An object lau

ikadub [295]

Answer:

v = √ 2 G M/ $R_{e}$

Explanation:

To find the escape velocity we can use the concept of mechanical energy, where the initial point is the surface of the earth and the end point is at the maximum distance from the projectile to the Earth.

Initial

Em₀ = K + U₀

Final

$Em_{f}$ = $U_{f}$

The kinetic energy is k = ½ m v²

The gravitational potential energy is U = - G m M / r

r is the distance measured from the center of the Earth

How energy is conserved

Em₀ = $Em_{f}$

½ mv² - GmM / $R_{e}$ = -GmM / r

v² = 2 G M (1 / $R_{e}$ – 1 / r)

v = √ 2GM (1 / $R_{e}$ – 1 / r)

The escape velocity is that necessary to take the rocket to an infinite distance (r = ∞), whereby 1 /∞ = 0

v = √ 2GM / $R_{e}$

5 0

3 years ago

Explain the change of frequency of the wave if the tension of the string is increased

jek_recluse [69]

Answer:

Increasing the tension on a string increases the speed of a wave, which increases the frequency (for a given length). Pressing the finger at different places changes the length of string, which changes the wavelength of standing wave, affecting the frequency.

Explanation:

8 0

2 years ago

Two electrodes, separated by a distance d, in a vacuum are maintained at a constant potential difference. An electron, accelerat

Alja [10]

Answer:

Explanation:

Given that, the distance between the electrode is d.

The electron kinetic energy is Ek when the electrode are at distance "d" apart.

So, we want to find the K.E when that are at d/3 distance apart.

K.E = ½mv²

Note: the mass doesn't change, it is only the velocity that change.

Also,

K.E = Work done by the electron

K.E = F × d

K.E = W = ma × d

Let assume that if is constant acceleration

Then, m and a is constant,

Then,

K.E is directly proportional to d

So, as d increase K.E increase and as d decreases K.E decreases.

So,

K.E_1 / d_1 = K.E_2 / d_2

K.E_1 = E_k

d_1 = d

d_2 = d/3

K.E_2 = K.E_1 / d_1 × d_2

K.E_2 = E_k × ⅓d / d

Then,

K.E_2 = ⅓E_k

So, the new kinetic energy is one third of the E_k

7 0

3 years ago

A boat produced water waves of frequency 4 Hz and wavelength 2m, if it reached the shore after 2 seconds how far is the boat fro

kap26 [50]

Answer:

S = 16 m

Explanation:

Given that

The frequency of the water waves, f = 4 Hz

The wavelength of the water waves, λ = 2 m

The time the waves reached the shore, t = 2 s

The relation between the velocity, wavelength, and the frequency of the wave is given by the relation,

v = f λ m/s

Substituting the given values in the above equation,

v = 4 x 2

= 8 m/s

The velocity of the water waves is v = 8 m/s

The distance between the shore and boat is given by

s = v x t

= 8 x 2

= 16 m

Hence, the distance between the boat and the shore is, s = 16 m

7 0

3 years ago

How do particles move when a surface wave passes through a medium?

kaheart [24]

They move in a perpendicular direction to the direction of wave motion. Happy to help!

8 0

2 years ago