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2 years ago

Use the periodic table and your knowledge of isotopes to complete these statements.

2 answers:

7 0

Use the periodic table and your knowledge of isotopes to complete these statements.

When polonium-210 emits an alpha particle, the child isotope has an atomic mass of ⇒ 206.

I-131 undergoes beta-minus decay. The chemical symbol for the new element is ⇒ Xe.

Fluorine-18 undergoes beta-plus decay. The child isotope has an atomic mass of ⇒ 18.

sleet_krkn [62]2 years ago

7 0

Answer:

206,Xe,18

Explanation:

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A 4.0 kg block is resting on a rough horizontal table. The coefficient of static friction us is 0.60. The static friction betwee

professor190 [17]

Answer: 24 N

Explanation:

Given that the

Mass m = 4 kg

Coefficient of friction (μ) = 0.60

To calculate the static friction between the block and the table before any attempted motion, you will use the formula; F = (μ)N

Where

F = static friction

N = normal reaction = mg

g = acceleration due to gravity = 9.8 m/^2

Substitutes m, g and (μ) into the formula

F = 0.6 × 4 × 9.8

F = 23.52 N

Therefore, the static friction between the block and the table before any attempted motion is 24 N approximately.

6 0

2 years ago

On a hypothetical scale X The ice point is 40° and steam point is 120°.

arlik [135]

Answer:

The reading of Y is -10°.

Explanation:

For scale X, the ice point is 40° and steam point is 120°.

Difference between the two extremes for scales X = 120 - 40 = 80

For scale X, the ice point and steam points are -30° and 130° respectively.

Difference between the two extremes for scales X = 130 - (-30) = 160

Comparing both scales:

One unit of scale X = x

One unit of scale Y = y

Scale X has 80 divisions while scale Y has 160

80x = 160y

x = 2y

50° in scale X = 10x + ice point in X scale

10 divisions in Y scale = 20y

Reading of Y scale = ice point of Y + 20y

= -30° + 20°

= -10°

7 0

2 years ago

While dangling a hairdryer by its cord, you observe that the cord is vertical when the hairdryer isoff and, once it is turned on

jekas [21]

Answer:

The speed of the air leaving the hairdryer is 10m/s.

Explanation:

The thrust that the dryer produces is what keeps it elevated at an angle of 5° from the vertical; therefore, from the force diagram we get

$(1).\: tan (5^o) = \dfrac{F_t}{Mg}$

putting in $M =0.420kg$ , $g = 9.8m/s^2$ and solving for $F_t$ we get:

$F_t = Mg\:tan(5^o)$

$F_t = (0.420kg)(9.8m/s^2)\:tan(5^o)$

$\boxed{F_t = 0.3601N.}$

Now, this thrust produced is related to to the air ejection speed $v$ by the relation

$(2).\: F_t = v\dfrac{dM}{dt}$

where $dM/dt$ is the rate of air ejection which we know is

$0.06m^3/2s = 0.03m^3/s$

and since $1m^3 = 1.2kg$ ,

$0.03m^3/s \rightarrow 0.036kg/s$

$\dfrac{dM}{dt} = 0.036kg/s,$

putting this into equation (2) and the value of $F_t$ we get:

$0.3601N = 0.036v$

which gives

$v= \dfrac{0.3601}{0.036}$

$\boxed{v =10m/s.}$

which is the speed of the air ejected.

6 0

2 years ago

A man runs at a velocity of 4.5 m/s for 15.0 min. When going up an increasingly steep hill, he slows down at a constant rate of

madreJ [45]

The man ran 4252.5 meters.

Why?

To solve the problem, we need to divide the exercise into two movements, the first on while the was running at 4.5 m/s for 15 min, and then, while he was slowing down (going up because of the hill).

First movement: Running at 4.5 m/s for 15 min.

We need convert from minutes to seconds,

$1min=60seconds\\\\15min*\frac{60seconds}{1min}=900seconds$

Now, calculating the distance covered for the first movement, we have:

$x_{1}=0+v_{1}*t_{1}\\\\x_{1}=4.5\frac{m}{s}*900s=4050m$

So, we know that the man covered 4050m for the first movement, it will be our initial position for the second movement.

Second movement: acceleration -0.05m/s^2 (because he's slowing down) for 90 seconds, at 4.5m/s.

$x_{2}=x_{1}+v_{1}*t+\frac{1}{2}at^{2}\\\\x_{2}=4050m+4.5m\frac{m}{s}*90seconds-\frac{1}{2}*(0.05\frac{m}{s^{2}})*(90s)^{2}\\\\x_{2}=4050m+405m-(0.5*0.05\frac{m}{s^{2}}*8100s^{2})=4050m+405m-202.5m\\\\x_{2}=4252.5m$

Hence, we have that he ran 4252.5 m.

Have a nice day!

4 0

2 years ago

Sea level is currently rising at 3.2 mm/yr, and scientists predict that global warming could cause a rise in sea level of 7 m if

Dovator [93]

Answer:

2188 years

Explanation:

given,

see level rising at the rate = 3.2 mm/yr

height of the sea level to rise = 7 m

time it will take rise 7 m = ?

we know,

1 m = 1000 mm

1 mm = 0.001 m

rate of increase of rate = 0.0032 m/year

time taken to rise = $\dfrac{7}{0.0032}\ years$

= 2187.5 years

Now, time taken by the sea level to rise 7 m is equal to 2188 years.

7 0

2 years ago