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3 years ago

13

A track athlete jumps over a hurdle. What is the equal and opposite force for the force of the athlete pushing on the ground as

described by Newton's third law?

1 answer:

Jet001 [13]3 years ago

6 0

Answer: Normal Force of the ground pushing the athlete up.

Explanation: I did this on Khan Academy and got the answer right.

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Which, if any, of the heat engines violate(s) the second law of thermodynamics?

Anuta_ua [19.1K]

The second law states that the total entropy can never decrese over time for an isolated system

3 0

3 years ago

What are the uses of rockets

lora16 [44]

They are used to be able to go out of Earth and into space to Be able to explore and toBe able to prove and tell about Earth and space

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3 years ago

Use the mass spectrum of europium to determine the atomic mass of europium. where the peak representing eu-151 has an exact mass

slavikrds [6]

Answer: The atomic mass of a Europium atom is 151.96445 amu.

From the given information:

Percent intensity is 91.61% of Europium atom of molecular weight 150.91986 amu.

Percent intensity is 100.00% of Europium atom of molecular weight 152.92138 amu.

Abundance of Eu-151 atom:

$X_{Eu-151}=\frac{0.9161}{0.9161+1.000}=0.4781$

Abundance of Eu-153 atom:

$X_{Eu-153}=\frac{1.000}{0.9161+1.000}=0.5219$

Atomic mass of Europium atom:

$A=(X_{Eu-151}\times150.91986+X_{Eu-153}\times152.92138)amu\\A=(0.4781\times150.91986+0.5219\times152.92138)amu=151.96445 amu$

Therefore, the atomic mass of a Europium atom is 151.96445 amu.

3 0

3 years ago

Read 2 more answers

If we have a one-electron atom, and the electron can occupy any of 5 different energy levels, and transitions are possible betwe

xeze [42]

Answer:

10

Explanation:

Lets say that a,b,c,d,e are the five allowed energy states in order of decreasing energy. Then the number of possible different spectral lines comes from the electron dropping from a high state to a lower state. So, they will do so in following ways:

a - b

a - c

a - d

a- e

b - c

b - d

b- e

c - d

c- e

d- e

Ans- Ten different possible energy jumps giving six different colors or lines in the spectrum.

7 0

3 years ago

In classical physics, consider a 2 kg block hanging on a spring with a spring constant of 50 N/m. Ignore air resistance. The blo

RUDIKE [14]

Answer:

v = 0

Explanation:

This problem can be solved by taking into account:

- The equation for the calculation of the period in a spring-masss system

$T = \sqrt{\frac{m}{k} }$ ( 1 )

- The equation for the velocity of a simple harmonic motion

$x = \frac{2\pi }{T}Asin(\frac{2\pi }{T}t)$ ( 2 )

where m is the mass of the block, k is the spring constant, A is the amplitude (in this case A = 14 cm) and v is the velocity of the block

Hence

$T = \sqrt{\frac{2 kg}{50 N/m}} = 0.2 s$

and by reeplacing it in ( 2 ):

$v = \frac{2\pi }{0.2s}(14cm)sin(\frac{2\pi }{0.2s}(0.9s)) = 140\pi sin(9\pi ) = 0$

In this case for 0.9 s the velocity is zero, that is, the block is in a position with the max displacement from the equilibrium.

5 0

3 years ago