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Valentin [98]
4 years ago
13

Many people believe that the atomic number of the atom is the number of electrons in the atom. Describe when this is the case

Physics
2 answers:
zepelin [54]4 years ago
5 0
<span> <span> <span> <span> When the atom is neutral and the number of electrons and the number of protons are equal. </span></span></span></span>
lesya [120]4 years ago
4 0

Answer: The  atomic number of the atom is the number of electrons in the atom only when the atom is neutral.

Explanation: For a neutral atom, the number of positive charges is equal to the number of negative charges and thus the atomic number is equal to the number of electrons or the number of protons.

But for a positive and a negative ion, the electrons are lost and gained respectively by that element and thus the number of electrons are not equal to the number of protons. Now atomic number is equal to the number of protons only. The number of electrons = number of protons - charge.

Example: For sodium Na , the atomic number is 11 and it has 11 electrons.

For sodium ion Na^+ , the atomic number is 11 but the number of electrons = (11-1) = 10.

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A car moves along an x axis through a distance of 900 m, starting at rest (at x = 0) and ending at
OlgaM077 [116]
A car moves along an x axis through a distance of 900 m, starting at rest (at x = 0) and ending at rest (at x = 900 m). Through the first 1/4 of that distance, its acceleration is +6.25 m/s2. Through the next 3/4 of that distance, its acceleration is -2.08 m/s2. What are (a) its travel time through the 900 m and (b) its maximum speed? 

<span>Solve for the time at the 1/4 mark. That's 225 m. How? d = (1/2)at^2 ( initial velocity zero). Thus 225 = (1/2) 6.25 t^2. t^2 = ( 225 * 2 ) / 6.25. t = 8.5 sec. </span>

<span>At the other end t^2 = (675 * 2) / 2.08 -- we reversed the sign and ran time backwards. t = 25.5 sec. </span>

<span>So total time is 8.5 + 25.5 or 34 sec. </span>

<span>Since zero initial velocity: v^2 = 2 a d. Here, v^2 = 2 * 6.25 * 225. v = 53 m/s. That's the fastest speed since braking then occurs.</span>
7 0
4 years ago
Plz solve this. plz plz plz plz simple machine ​
nalin [4]

Answer:

Explanation:

i.  CW moment = 10 N (10 cm) + 30 N (30 cm) - 60 N (40 cm) = - 1400 N-cm

ii.  ACW momenet = 60 N (40 cm) - 10 N (10 cm) + 30 N (30 cm) = 1400 N-cm

iii.  No. The lever is not balanced in the situation. Because the moment is ± 1400 N-cm.  if balance, the moment must be Zero.

iv.   the location of 10N by keeping the other loads unchanged to balance the lever is 150 cm

take moment from Δ (support)

60(40) = 10(x) + 30(30)

2400 = 10x + 900

10x = 2400 - 900

10x = 1500

x = 1500/10

x = 150 cm  

therefore, the location of 10N by keeping the other loads unchanged to balance the lever is 150 cm

5 0
3 years ago
(30 points) Air at 500 kPa and 400 K enters an adiabatic nozzle at a velocity of 30 m/s and leaves at 300 kPa and 350 K. Using v
Sophie [7]

Answer:

Explanation:

Check attachment for solution

8 0
3 years ago
Two parallel-plate capacitors, identical except that one has twice the plate separation of the other, are charged by the same vo
erik [133]

Answer:

The capacitor having less distance of separation has a stronger electric field.

Explanation:

The capacitors are identical and only difference between them is that one has twice the plate separation of the other. Therefore, capacitance of the given capacitors C1 and C2 is,

C1= Aε/d  and C2=Aε/2d

The charges Q1 and Q2 on the capacitors of capacitance C1 and C2 respectively, is then given by the equation,

Q1=VC1

Q1=VAε/d

Q2=VC2

Q2=VAε/2d

Therefore, the surface charge density σ1 and σ2 for the capacitors is,

σ1=Q1/A

σ1=VAε/(d*A)

σ1=Vε/d

Similarly,

σ2=Q2/A

σ2=Vε/2d

The electric field between the plates is directly proportional to the surface charge density. And so electric field is inversely proportional to the distance of separation. Therefore the capacitor whose distance of separation is less has a stronger electric field.

Check out similar questions.

brainly.com/question/14744776

#SPJ10

8 0
2 years ago
A car accelerates uniformly from rest to a speed of 7.6 m/s in 4.6 s. How far does the car travel in that time?
uysha [10]

Answer:

The car will travel a distance of 17.45 meters.

Explanation:

Given:

Initial velocity (V_i) = 0

Final velocity (V_f) = 7.6 m/s

Time taken = 4.6 s

Acceleration = (Final velocity - Initial Velocity )/time

a=\frac{(V_f-Vi)}{t}= \frac{7.6-0}{4.6}=1.65\ ms^-2

We have to calculate total distance traveled by the car.

Let the distance traveled be 'd'

Equation of motion:

d=V_i(t)+\frac{at^2}{2}

Plugging the values.

⇒d=V_i(t)+\frac{at^2}{2}

⇒d=0+\frac{1.65*(4.6)^2}{2}

⇒d=17.45\ m

The car will travel a distance of 17.45 meters for the above case.

4 0
3 years ago
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