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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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A truck driving east on a highway goes from the 42 mi marker to the 48 mi

Leona [35]

Average velocity is 1..2 mi/min east

Explanation:

Velocity = Displacement/Time

Here, displacement = 48 mi - 42 mi = 6 miles

Time = 5 minutes

⇒ Average Velocity = 6/5 = 1.2 mi/min east

3 0

3 years ago

A student holds a bike wheel and starts it spinning with an initial angular speed of 9.0 rotations per second. The wheel is subj

KATRIN_1 [288]

Answer:

$\Delta t = 8 s$

Explanation:

As we know that the angular acceleration of the wheel due to friction is constant

so we can use kinematics

$\theta = \omega_i t + \frac{1}{2}\alpha t^2$

so we have

$(65 \times 2\pi) = (2\pi \times 9)(10) + \frac{1}{2}(\alpha)(10^2)$

$130\pi = 180\pi + 50 \alpha$

$\alpha = -\pi rad/s^2$

now time required to completely stop the wheel is given as

$\omega_f = \omega_i + \alpha t$

$0 = (2\pi \times 9) + (-\pi) t$

$t = 18 s$

now time required to stop the wheel is given as

$\Delta t = 18 - 10$

$\Delta t = 8 s$

6 0

3 years ago

A spring stretches 0.018 m when a 2.8-kg object is suspendedfrom its end. How much mass should be attached to this spring sothat

agasfer [191]

Answer:

m = 4.29 kg

Explanation:

Given that,

Mass of the object, m = 2.8 kg

Stretching in the spring, x = 0.018 m

Frequency of vibration, f = 3 Hz

Let m is the mass of the object that is attached to the spring. When it is attached the gravitational force is balanced by the force on spring. It is given by :

$mg=kx$

$k=\dfrac{mg}{x}$

$k=\dfrac{2.8\times 9.8}{0.018}$

k = 1524.44 N/m

Since, $\omega=\sqrt{\dfrac{k}{m}}$

$m=\dfrac{k}{4\pi^2 f^2}$

$m=\dfrac{1524.44}{4\pi^2 \times 3^2}$

m = 4.29 kg

So, the mass that is attached to this spring is 4.29 kg. Hence, this is the required solution.

4 0

3 years ago

Anybody knows ? mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm .

notsponge [240]

Answer:

I think it's because it's an insulator and like charges attract

6 0

3 years ago

Suppose you are planning a trip in which a spacecraft is to travel at a constant velocity for exactly six months, as measured by

QveST [7]

Answer:

0.999958c

Explanation:

Remember that the trip involves traveling for six months at a constant velocity thus returning home at same speed . The time interval of this trip will therefore be one year.

Accurate time interval to be measured by the clock on the spaceship Δt0 = 1.0 years

Time interval as advanced on earth observed from the spacecraft Δt = 110 years

the formula for time dilation is

Δt = Δt0 /√(1-v2/c2)

or v = c*√1-(Δt0/Δt)2

=c*√[1-(1year/110years)2]

= 0.999958c

3 0

3 years ago