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insens350 [35]
2 years ago
4

6. Regarding the formula Al2O3 which of the following is accurate? A. The coefficient 3 indicates that there are a total of thre

e atoms of oxygen present in the substance. B. The subscript 2 indicates that two atoms of oxygen are present in the substance. C. The chemical symbol Al indicates that oxygen is present in the substance. D. The subscript 2 indicates that two atoms of aluminum are present in the substance.
Physics
2 answers:
Leya [2.2K]2 years ago
6 0
The correct answer is D.
Natasha2012 [34]2 years ago
3 0

The correct answer is

D. The subscript 2 indicates that two atoms of aluminum are present in the substance.

In fact, the formula of the substance is

Al_2 O_3

the subscript 2 indicates that there are 2 atoms of Aluminium, while the subscript 3 indicates there are 3 atoms of oxygen, so option D is correct.

Option A is wrong because 3 is not a coefficient, is a subscript. Option B is wrong because the subscript 2 refers to the aluminium, not to the oxygen, and option C is wrong because the symbol Al refers to aluminium, not oxygen.

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What is the gravitational force of attraction between a planet and a 17-kilogram mass that is falling freely toward the surface
PolarNik [594]

Answer:

a. 150 N

Explanation:

Gravitational Force: This is the force that act on a body under gravity.

The gravitational force always attract every object on or near the earth's surface. The earth therefore, exerts an attractive force on every object on or near it.

The S.I unit of gravitational force is Newton(N).

Mathematically, gravitational force of attraction is expressed as

(i) F = GmM/r² ........................ Equation 1 ( when it involves two object of different masses on the earth)

(ii) F = mg ............................... Equation 2 ( when it involves one mass and the gravitational field).

Given: m = 17 kg, g = 8.8 m/s²

Substituting into equation 2,

F = 17(8.8)

F = 149.6 N

F ≈ 150 N.

Thus the gravitational force = 150 N

The correct option is a. 150 N

5 0
2 years ago
Tex, an 85.0 kilogram rodeo bull rider is thrown from the bull after a short ride. The 520. kilogram bull chases after Tex at 13
Julli [10]
The question above can be answered through using the concept of Conservation of Momentum which may be expressed as,
                 m1v1 + m2v2 = mTvT
where m1 and v1 are mass and initial velocity of Tex, 2s are that of the bull, and the Ts are the total. Then substituting,
                    (85 kg)(3 m/s) + (520 kg)(13 m/s) = (520 + 85)(vT)
The value of vT obtained from above equation is 11.6 m/s
3 0
2 years ago
6. Starting from 1.5 miles away, a car drives toward a speed checkpoint and then passes it. The car travels at a constant rate o
loris [4]
For the answer to the question above, 

<span>To be 0.1 miles away from the check point ,
 the car has to travel 1.4 miles OR 1.6 miles. </span>


53 miles = 60 minutes 

1.4 miles = 1.4 / 53 X 60 = 1.5849056 minutes OR 95.1 seconds 

<span>1.6 miles = 1.6 /53 X 60 = 1.8113207 minutes OR 108.7 seconds 
</span>So the answer is <span>95.1s and 108.7s
I hope my answer helped you</span>
7 0
2 years ago
Juan is standing on the street. An ambulance moves toward him and then passes by. What best describes the pitch that Juan hears?
ozzi

Answer: The correct answer is "the pitch drops to a lower pitch once the ambulance passes by Juan".

Explanation:

Doppler effect is the phenomenon in which there is an increase or decrease in the frequency when there is relative motion between the source and listener.

Pitch depends on the frequency. if the frequency increases then pitch increases.

When the source and the listener are moving towards each other then there is increase in the frequency. When the source and the listener are moving away each other then there is decrease in the frequency.

In the given problem, Juan is standing on the street. An ambulance moves toward him and then passes by the pitch drops to a lower pitch once the ambulance passes by Juan.

5 0
2 years ago
Read 2 more answers
A vehicle has an initial velocity of v0 when a tree falls on the roadway a distance xf in front of the vehicle. The driver has a
Korvikt [17]

Answer:

v^2=v_o^2-2\times a\times (v_o.t)

Explanation:

Given:

Initial velocity of the vehicle, v_o

distance between the car and the tree, x_f

time taken to respond to the situation, t

acceleration of the car after braking, a

Using equation of motion:

v^2=u^2+2a.s ..............(1)

where:

v= final velocity of the car when it hits the tree

u= initial velocity of the  car when the tree falls

a= acceleration after the brakes are applied

s= distance between the tree and the car after the brakes are applied.

s=v_o\times t

Now for this situation the eq. (1) becomes:

v^2=v_o^2-2\times a\times (v_o.t) (negative sign is for the deceleration after the brake is applied to the car.)

5 0
2 years ago
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