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Firlakuza [10]
3 years ago
5

Which is a sign of a chemical change? A) Ice cream left at room temperature melts. B) Calcium chloride is dissolved in H2O and d

isappears. C) Paint on a freshly painted wall dries and is no longer sticky. D) When H2S gas is bubbled into a lead acetate solution, a precipitate forms.
Physics
2 answers:
Eduardwww [97]3 years ago
7 0

D, because a physical change is when something changes but doesn't change into a new substance. A chemical change is when something changes into a new substance.

Katarina [22]3 years ago
5 0
Chemical change is any change that results in the formation of new chemical substances. (Thanks to google)

This the answer is D
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Ac soucre change it polarity how many time
Karolina [17]
Alternating current (AC) flows half the time in one direction and half the time in the other, changing its polarity 120 times per second with 60-hertz current.
6 0
2 years ago
The diagram shows a ballistic pendulum. A 200 g bullet is fired into the suspended 4 kg block of wood and remains embedded insid
adoni [48]

Question

What was the initial momentum of the bullet before collision?

Answer:

10 Kg.m/s

Explanation:

Momentum is a product of velocity of an object in m/s and its mass in kgs hence numerically expressed as p=mv where p is momentum, v is velocity and m is mass. Substituting m for 0.2 kg and v for 50 m/s then p=0.2*50=10 kg.m/s

5 0
3 years ago
A young woman with normal distant vision has a 10.0% ability to accommodate (that is, increase) the lens strength (a.k.a, lens p
Kipish [7]

Answer:

20.0 cm

Explanation:

Here is the complete question

The normal power for distant vision is 50.0 D. A young woman with normal distant vision has a 10.0% ability to accommodate (that is, increase) the power of her eyes. What is the closest object she can see clearly?

Solution

Now, the power of a lens, P = 1/f = 1/u + 1/v where f = focal length of lens, u = object distance from eye lens and v = image distance from eye lens.

Given that we require a 10 % increase in the power of the lens to accommodate the image she sees clearly, the new power P' = 50.0 D + 10/100 × 50 = 50.0 D + 5 D = 55.0 D.

Also, since the object is seen clearly, the distance from the eye lens to the retina equals the distance between the image and the eye lens. So, v = 2.00 cm = 0.02 m

Now, P' = 1/u + 1/v

1/u = P'- 1/v

1/u = 55.0 D - 1/0.02 m

1/u = 55.0 m⁻¹ - 1/0.02 m

1/u = 55.0 m⁻¹ - 50.0 m⁻¹

1/u = 5.0 m⁻¹

u = 1/5.0 m⁻¹

u = 0.2 m

u = 20 cm

So, at 55.0 dioptres, the closet object she can see is 20 cm from her eye.

8 0
2 years ago
A 1.5-kilogram cart initially moves at 2.0 meters per second. It is brought to rest by a constant net force in 0.30 second. What
AnnZ [28]
Acceleration = (change in speed) / (time for the change)

Change in speed = (speed at the end) minus (speed at the beginning.

The cart's acceleration is

                               (0 - 2 m/s) / (0.3 sec)

                           = ( -2 / 0.3 ) (m/s²)  =  -(6 and 2/3) m/s² .

Newton's second law of motion says

                             Force = (mass) x (acceleration) .

For this cart:      Force = (1.5 kg) x ( - 6-2/3 m/s²)

                                       = ( - 1.5 x 20/3 ) (kg-m/s²)

<span>                                       =      </span>- 10 newtons .

<span>The force is negative because it acts opposite to the direction </span>
<span>in which the cart is moving, it causes a negative acceleration, </span>
<span>and it eventually stops the cart.</span>
6 0
2 years ago
What is the momentum of a 200 kg football player running west at a speed of 8m/s
lutik1710 [3]

Answer:

<h3>The answer is 1600 kgm/s</h3>

Explanation:

The momentum of an object can be found by using the formula

<h3>momentum = mass × velocity</h3>

From the question

mass = 200 kg

velocity / speed = 8m/s

We have

momentum = 200 × 8

We have the final answer as

<h3>1600 kgm/s</h3>

Hope this helps you

7 0
3 years ago
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