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Anarel [89]
3 years ago
15

There is a 50 g sample of Ra-229. It has a half-life of 4 minutes.

Physics
1 answer:
Sloan [31]3 years ago
4 0

Via half-life equation we have:


A_{final}=A_{initial}(\frac{1}{2})^{\frac{t}{h} }


Where the initial amount is 50 grams, half-life is 4 minutes, and time elapsed is 12 minutes.  By plugging those values in we get:

A_{final}=50(\frac{1}{2})^\frac{12}{4}=50(\frac{1}{2})^{3}=50(\frac{1}{8})=6.25g


There is 6.25 grams left of Ra-229 after 12 minutes.

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A 15g bullet is fired horizontally into a 3kg block of wood suspended by a long cord. Assume that the bullet remains in the bloc
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Answer:

261.3 m/s

Explanation:

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1 kg=1000g

Mass of block=M=3 kg

d=0.086 m

Total mass =M+m=3+0.015=3.015 kg

K.E at the time strike=Gravitational potential energy at the end of swing

\frac{1}{2}(m+M)^2V^2=(m+M)gh

Using g=9.8m/s^2

Substitute the values

\frac{1}{2}(3.015)V^2=3.015\times 9.8\times 0.086

V^2=\frac{2\times 3.015\times 9.8\times 0.086}{3.015}

V=\sqrt{2\times 3.015\times 9.8\times 0.086}}

V=1.3m/s

Velocity after collision=V=1.3 m/s

Velocity of block=v'=0

Using conservation law of momentum

mv+Mv'=(m+M)V

Using the formula

0.015v+3(0)=3.015(1.3)

0.015v=3.015(1.3)

v^2=\frac{3.015(1.3)}{0.015}=261.3

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5 0
3 years ago
An overtone that's a whole number multiple of the fundamental frequency of a string is called a
alina1380 [7]
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6 0
3 years ago
How long will it take a ball to roll 10 meters along the floor at a speed of 0.5m/s
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Answer:

5s

Explanation:

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5 0
11 months ago
A 1280 kg car is moving 4.92 m/s. a 509 N force then pushes it forward for 28.7 m. what is its final KE?(unit=J)PLEASE HELP
laila [671]

Answer:

The answer to your question is: total energy = 30100.4 J

Explanation:

Kinetic energy (KE) is the energy due to the movement of and object, its units are joules (J)

Data

mass = 1280 kg

speed = 4.92 m/s

Force = 509 N

distance = 28.7 m

Formula

KE = \frac{1}{2} mv^{2}

Work = Fd

Process

- Calculate Kinetic energy

- Calculate work

- Add both results

KE = \frac{1}{2} (1280)(4.92)^{2}

KE = 15492.1 J

Work = (509)(28.7)

Work = 14608.3 J

Total = 15492.1 + 14608.3

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3 years ago
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B. is the answer.

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