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aleksklad [387]
3 years ago
8

Erica (38 kgkg ) and Danny (46 kgkg ) are bouncing on a trampoline. Just as Erica reaches the high point of her bounce, Danny is

moving upward past her at 4.9 m/sm/s . At that instant he grabs hold of her.
Physics
1 answer:
salantis [7]3 years ago
6 0

Answer:

The speed with which just after he grabs her is 2.68 m/s.

Explanation:

Given that,

Mass of Erica, m = 38 m/s

Mass of Danny, m' = 46 kg

Erica reaches the high point of her bounce, Danny is moving upward past her at 4.9 m/s. At this moment, the initial speed of Erica will be 0. The momentum will remain conserved. Using the conservation of linear momentum as :

mu+m'u'=(m+m')V\\\\0+46\times 4.9=(38+46)V\\\\V=\dfrac{225.4}{84}\\\\V=2.68\ m/s

So, the speed with which just after he grabs her is 2.68 m/s. Hence, this is the required solution.

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At what displacement of a sho is the energy half kinetic and half potential? what fraction of the total energy of a sho is kinet
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As we know that KE and PE is same at a given position

so we will have as a function of position given as

KE = \frac{1}{2}m\omega^2(A^2 - x^2)

also the PE is given as function of position as

PE = \frac{1}{2}m\omega^2x^2

now it is given that

KE = PE

now we will have

\frac{1}{2}m\omega^2(A^2 - x^2) = \frac{1}{2}m\omega^2x^2

A^2 - x^2 = x^2

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Part b)

KE of SHO at x = A/3

we can use the formula

KE = \frac{1}{2}m\omega^2(A^2 - x^2)

now to find the fraction of kinetic energy

f = \frac{KE}{TE} = \frac{A^2 - x^2}{A^2}

f = \frac{A^2 - (\frac{A}{3})^2}{A^2}

f_k = \frac{8}{9}

now since total energy is sum of KE and PE

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f_{PE} = 1 - f_k

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3 years ago
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As per the question the wavelength of spectral line of the neutral hydrogen atom is 21 cm.

Spectral line of hydrogen atom will be observed when an electron will jump from higher excited to the ground state. If E is the energy of the ground state and E' is the energy of the higher excited state,the energy emitted when electron will jump from higher excited to ground state is E'-E.

As per Planck's quantum theory -

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