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3 years ago

For the examples below, explain what a physical change or a chemical change has occurred. Justify your answer

1 answer:

4 0

A. chemical change, a new substance is formed and the effect cannot be undone.
B.physical change, there is no new substance made and the effect can be undone
C.chemical change, the effect cannot be undone
D.physical change, the effect can be undone
E.chemical change, a new substance is made and the effect cannot be undone
F.physical change, there is no new substance and the effect can be reversed

hope this helps :)

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4. An object is thrown vertically upward with a speed of 25 m/s. How much time passes before it

vlada-n [284]

Answer:

Option b is correct: 4.1 s

Explanation:

Vertical Launch

An object launched thrown vertically upward where air resistance is negligible, reaches its maximum height in a time t, given by the equation:

$\displaystyle t=\frac{v_o}{g}\qquad\qquad[1]$

Where vo is the initial speed and g is the acceleration of gravity g=9.8 $m/s^2$ .

Once the object reaches that point, it starts a free-fall motion, whose speed is (downward) given by:

$v_f=g.t\qquad\qquad[2]$

The object considered in the question is thrown with vo=25 m/s. The time taken to reach the maximum height is given by [1]:

$\displaystyle t=\frac{25}{9.8}=2.551\ sec$

The object starts its falling motion and at some time, it has a speed of vf=15 m/s. Let's find the time by solving [2] for t:

$\displaystyle t=\frac{15}{9.8}=1.531\ sec$

The total time taken by the object to go up and down is

$t_t=2.551\ s+1.531\ s=4.081\ s$

a. This option is incorrect because it's far away from the answer.

d. This option is incorrect because it's far away from the answer.

b. This option is correct because it's a good approximation to the calculated answer.

e. This option is incorrect because it's far away from the answer.

c. This option is incorrect because it's far away from the answer.

5 0

3 years ago

The momentum of a car is 13,300 kgm/s. If it has a speed of 14 m/s, what is the mass of the car?

Tamiku [17]

By definition we have that the linear moment is
p = m * v
Where
m = mass
v = speed.
Clearing the mass we have
m = p / v
Substituting the values
m= (13,300 kgm/s)/(14 m/s)=950Kg
the mass of the car is 950 Kg

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3 years ago

‼️‼️‼️‼️ Which type of force is she demonstrating in this position? static friction rolling friction sliding friction fluid fric

Lana71 [14]

A) STATIC FRICTION, that’s the position she is demonstrating against the way she is on!!!!

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3 years ago

What is surface tension of water? Please help!

kondaur [170]

Surface tension could be defined as the property of the surface of a liquid that allows it to resist an external force. The cohesive forces among liquid molecules are responsible for the phenomenon.

In simpler terms, it is the force that causes the molecules on the surface of a liquid to be pushed together and form a layer. The surface tension, then, is a measure of the cohesive forces that hold the molecules together.

Getting the actual measurement would give us 72 dynes/cm at 25°C . However, the force decreases significantly depending on the temperature.

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4 years ago

What controls the brain of a cell

olya-2409 [2.1K]

The nucleus of course...

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4 years ago