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4 years ago

What are the three reasons cells divide?

1 answer:

7 0

1 growth. Go from one cell/( zygote to a trillion)
2 replace. Repair\ 50 million cells die second.
3 reproduction. ( make cells for reproduction make specialized sex cells)

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A 3.00 kg object is fastened to a light spring, with the intervening cord passing over a pulley. The pulley is frictionless, and

finlep [7]

Answer:

Part a)

k = 588.6 N/m

Part b)

v = 0.7 m/s

Explanation:

As we know that initially block is at rest

now if block is released from rest then it will go down by 10 cm and again comes to rest

so here we have

Part a)

Work done by gravity + work done by spring force = change in kinetic energy

$W_g + W_{spring} = 0 - 0$

$mg(0.10) + \frac{1}{2}k(0^2 - 0.10^2) = 0$

$3(9.81)(0.10) - \frac{1}{2}k(0.10)^2 = 0$

$k = 588.6 N/m$

Part b)

Now when spring is stretch by x = 5 cm then the speed of the block is given as

$mgx' + \frac{1}{2}k(0^2 - x'^2) = \frac{1}{2}mv^2 - 0$

here we have

$x' = 0.05 m$

$3(9.81)(0.05) - \frac{1}{2}(588.6)(0 - 0.05^2) = \frac{1}{2}(3) v^2$

$1.4715 - 0.736 = 1.5 v^2$

$v = 0.7 m/s$

3 0

3 years ago

Explain why the roller coaster’s potential energy is greater at point 1 than at point 4.

lesya692 [45]

Point 1 is PROBABLY higher up than point 4.

Another possibility is that on the way from Point 1 to point 4,
a lot of people are falling out of the coaster.

We have no way to tell, because you neglected to show us
the picture that goes with this question. It's important.

5 0

4 years ago

Read 2 more answers

A mass on the end of a spring undergoes simple harmonic motion. At the instant when the mass is at its equilibrium position, wha

Paha777 [63]

Answer:

3.At equilibrium, its instantaneous velocity is at maximum

Explanation:

The motion of a mass on the end of a spring is a simple harmonic motion. In a simple harmonic motion, the total mechanical energy of the system is constant, and it is sum of the elastic potential energy (U) and the kinetic energy of the mass (K):

$E=U+K=\frac{1}{2}kx^2+\frac{1}{2}mv^2 = const.$

where

k is the spring constant

x is the displacement of the spring from equilibrium

m is the mass

v is the speed

As we see from the formula, since the total energy E is constant, when the displacement (x) increases, the speed (v) increases, and viceversa. Therefore, when the mass is at its equilibrium position (which corresponds to x=0), the velocity of the mass will be maximum.

7 0

3 years ago

What is the independent variable on this graph??

Veronika [31]

Temperature. X-axis is always the independent variable.

3 0

4 years ago

Read 2 more answers

In each of the parts of this question, a nucleus undergoes a nuclear decay. Determine the resulting nucleus in each case.

MA_775_DIABLO [31]

A) Francium-223

In an alpha decay, a nucleus decay emitting an alpha particle, which corresponds to a nucleus of helium: so, it consists of 2 protons and 2 neutrons.

$X \rightarrow X' + \alpha$

This means that in the decay:

- The original nucleus loses 2 protons --> so its atomic number Z decreases by 2 units

- The original nucleus loses 2 nucleons (2 protons and 2 neutrons) --> so its mass number A decreases by 4 units

In this example, the original nucleus is Ac (Actinium), with

Z = 89

A = 227

After the decay, it must be

Z - 2 = 89 - 2 = 87

A - 4 = 227 - 4 = 223

We see from the periodict table, Z=87 corresponds to Francium (Fr), so the final nucleus will be francium-223 (the isotope of francium with 223 nucleons).

B) Polonium-211

In a beta-minus decay, a neutron in the nucleus turns into a proton, emitting a fast-moving electron (the beta particle) and an anti-neutrino.

$n \rightarrow p + e^- + \bar{\nu}$

Therefore, in this process:

- The original nucleus gains 1 protons, so its atomic number Z increases by 1 unit

- The original nucleus does not lose/gain nucleons, so its mass number A remains the same

In this example, the original nucleus is Bi (bismuth)-211, with

Z = 83

A = 211

So After the decay, it will be

Z + 1 = 83 + 1 = 84

A = 211

So, the nucleus will be Polonium (Z=84), isotope with 211 nucleons.

C) Neon-22

In a beta-plus decay, a proton in the nucleus turns into a neutron, emitting a fast-moving positron (the beta particle) and a neutrino.

$p \rightarrow n + e^+ +\nu$

Therefore, in this process:

- The original nucleus loses 1 protons, so its atomic number Z decreases by 1 unit

- The original nucleus does not lose/gain nucleons, so its mass number A remains the same

In this example, the original nucleus is Na (sodium)-22, with

Z = 11

A = 22

So After the decay, it will be

Z - 1 = 11 - 1 = 10

A = 22

So, the nucleus will be Neon (Z=10), isotope with 22 nucleons.

D) Technetium-98

In a gamma decay, an unstable nucleus emits a gamma ray:

$X' \rightarrow X + \gamma$

In this process, only energy is released (in the form of gamma ray), so there is no gain/loss of protons/neutrons in the process. This means that:

- The atomic number Z remains constant

- The mass number A remains constant

In this example, we have a nucleus of Tc (Technetium)-98, with

Z = 43

A = 98

These numbers will not change during the decay: this means that after the decay, we will still have a nucleus of Technetium-98.

8 0

4 years ago