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3 years ago

Help!! Thank You!! Potassium has 19 protons. How many electrons does a neutral potassium atom have?

2 answers:

8 0

A neutral atom... no matter what the element... has the same number of protons and electrons. In this case, 19 electrons are needed.

Alisiya [41]3 years ago

7 0

19, because the number of protons and electrons are the same!

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What is the symbol for momentum

Elina [12.6K]

The most common symbol for momentum is p

8 0

4 years ago

Read 2 more answers

A toy car is given a quick push so that it moves up an inclined ramp. After it is released, it moves up, reaches its highest poi

Alexeev081 [22]

Answer:

7. Net constant force down the ramp

Explanation:

After the car is released and starts moving up the ramp, the only force that is applied on the car is weight because of the gravity, we were told that the friction force is neglected. the force because of the weight is given by:

$F=m*g*sin(\theta)$

where θ is the angle of the ramp.

as you can see those values won't change, so the force remains constant down the ramp.

4 0

3 years ago

Water flows with constant speed through a garden hose that goes up to 27.5 cm high. if the water pressure is 132kpa at the botto

sergejj [24]

Answer:

The pressure at the top of the step is 129.303 kilopascals.

Explanation:

From Hydrostatics we find that the pressure difference between extremes of the water column is defined by the following formula, which is a particular case of the Bernoulli's Principle ( $v_{bottom}\approx v_{top}$ ):

$p_{bottom}-p_{top} = \rho\cdot g\cdot \Delta h$ (1)

$p_{bottom}$ , $p_{top}$ - Total pressures at the bottom and at the top, measured in pascals.

$\rho$ - Density of the water, measured in kilograms per cubic meter.

$\Delta h$ - Height difference of the step, measured in meters.

If we know that $p_{bottom} = 132000\,Pa$ , $\rho = 1000\,\frac{kg}{m^{3}}$ , $g = 9.807\,\frac{m}{s^{2}}$ and $\Delta h = 0.275\,m$ , then the pressure at the top of the step is:

$p_{top} = p_{bottom}-\rho\cdot g\cdot \Delta h$

$p_{top} = 132000\,Pa-\left(1000\,\frac{kg}{m^{3}} \right)\cdot \left(9.807\,\frac{m}{s^{2}} \right)\cdot (0.275\,m)$

$p_{top} = 129303.075\,Pa$

$p_{top} = 129.303\,kPa$

The pressure at the top of the step is 129.303 kilopascals.

6 0

3 years ago

A tall building is swaying back and forth on a gusty day. The wind picks up and doubles the amplitude of the oscillation. By wha

xz_007 [3.2K]

Answer:

by a factor of 2

Explanation:

Maximum speed of a body in simple harmonic motion relate to the amplitude by the following formula:

v ( maximum speed in m/s ) = x ( amplitude in meters ) √K /m where K is in N/m and m is kg

v is directly proportional to the amplitude and increases as the amplitude increases by a factor of 2

4 0

3 years ago

A giant wall clock with diameter d rests vertically on the floor. The minute hand sticks out from the face of the clock, and its

Katyanochek1 [597]

Answer:

$d_{x}(t)=(D/2)cos(\frac{\pi}{30}*t)$

Explanation:

We can try writing the equation of the horizontal component of the length of the minute hand in terms of distance and the angle, that depends of time in this particular case.

The x-component of the length of the minute hand is:

$d_{x}(t)=dcos(\theta (t))$ (1)

d is the length of the minute hand (d=D/2)
D is the diameter of the clock
t is the time (min)

Now, using the angular kinematic equations we can express the angle in term of angular velocity and time. As we know, the minute hand moves with a constant angular velocity, so we can use this equation:

$\theta (t)=\omega *t$ (2)

Also we know, that the minute hand moves 90 degrees or π/2 rad in 15 min, so using the definition of angular velocity, we have:

$\omega=\frac{\Delta \theta}{\Delta t}=\frac{\theta_{f}-\theta_{i}}{t_{f}-t{i}}=\frac{\pi/2-0}{15-0}=\frac{\pi}{30}$

Now, let's put this value on (2)

$\theta (t)=\frac{\pi}{30}*t$

Finally the length x(t) of the shadow of the minute hand as a function of time t, will be:

$d_{x}(t)=(D/2)cos(\frac{\pi}{30}*t)$

I hope it helps you!

6 0

3 years ago