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Anna35 [415]
3 years ago
5

When determining whether a chemical reaction has taken place, you observe and look for several indicators. Which would be consid

ered an indication that a chemical reaction or chemical change has taken place?
A) Solid melts.
B) Heat is given off.
C) Substance dissolves
D) Substance changes shape.
Physics
1 answer:
mixer [17]3 years ago
4 0
The answer would be B, heat is given off. Steam, bubbling, and fizzing can also indicate that a chemical change is occurring.  
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Two identical 0.400 kg masses are pressed against opposite ends of a light spring of force constant 1.75 N/cm, compressing the s
nlexa [21]

Answer:

0.853 m/s

Explanation:

Total energy stored in the spring = Total kinetic energy of the masses.

1/2ke² = 1/2m'v².................... Equation 1

Where k = spring constant of the spring, e = extension, m' = total mass, v = speed of the masses.

make v the subject of the equation,

v = e[√(k/m')].................... Equation 2

Given: e = 39 cm = 0.39 m, m' = 0.4+0.4 = 0.8 kg, k = 1.75 N/cm = 175 N/m.

Substitute into equation 2

v = 0.39[√(1.75/0.8)

v = 0.39[2.1875]

v = 0.853 m/s

Hence the speed of each mass = 0.853 m/s

7 0
3 years ago
Please help with these questions. All questions are in the image.​
S_A_V [24]

1) Average speed

2) Displacement

Explanation:

1)

Speed is a scalar quantity which gives a measure of how fast a body is moving. It is equal to the ratio between the distance travelled by an object and the time taken to cover that distance:

speed = \frac{d}{\Delta t}

where

d is the distance covered

\Delta t is the time taken

It is important to note that being a scalar, speed does not have any direction. Moreover, distance is also a scalar quantity, which corresponds to the total length of the path covered by the object, regardless on the direction taken.

So, the equation "travelled distance/elapsed time" corresponds to the average speed. (where the term average refers to the fact we are not measuring the speed at a specific instant in time, but on a certain time interval \Delta t.

2)

Velocity is a vector quantity, so it has both a magnitude and a direction.

The magnitude of the velocity is given by:

velocity=\frac{\Delta x}{\Delta t}

where

\Delta x is the change in position (or displacement) of the object

\Delta t is the time taken

And the direction of the velocity corresponds to the direction of the displacement.

We must note that while distance does not depend on the direction, displacement does. In fact, displacement measures the difference between the initial and final position of the object.

Therefore, the equation "change in position / elapsed time" is equal to the average velocity.

Learn more about speed and velocity:

brainly.com/question/8893949 (speed)

brainly.com/question/5063905 (speed vs velocity)

brainly.com/question/5248528 (velocity)

#LearnwithBrainly

4 0
3 years ago
Which of the following is true about light?
ale4655 [162]
Light travels in waves AND in bundles called "photons".

It's hard to imagine something that's a wave and also a bundle.
But it turns out that light behaves like both waves and bundles.

If you design an experiment to detect waves, then it responds to light.

And if you design an experiment to detect 'bundles' or particles, then
that one also responds to light.
7 0
3 years ago
Which is a vector quantity, speed or velocity? defend your answer.
krek1111 [17]
<span>Speed is the distance traveled divided by the time it took to travel this distance. Velocity is the change in position divided by the time of travel. Velocity only depends on the starting and ending point but the speed depends on the path. Speed is a scalar quantity (the distance per time ratio) and velocity is a vector quantuty, because it is defined also with its direction.</span>
4 0
3 years ago
Two sticks are suspended on silk thread, electrified by charges of opposite sign. Is there a magnetic field around them? An elec
IRINA_888 [86]

ANSWER and EXPLANATION

We want to identify if there will be an electric field and a magnetic field around the two sticks electrified by charges of opposite signs.

An electric field is a physical field that surrounds electrically charged particles and exerts a force on other charged particles in the surrounding.

This implies that the presence of electric charges on both sticks generates electric fields on them. Since the two charges are opposite, the electric force acting on them will be attractive.

Hence, there is an electric field.

A stationary charged object produces an electric field, as explained above, but will only produce a magnetic field if there is a motion of the object.

Hence, except the two sticks are caused to move, there will be no magnetic field around them.

5 0
1 year ago
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