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3 years ago

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Clarisse had three substances. A white substance was waxy and malleable. A red crystal was translucent, and it cracked when she

hit it with a hammer. A silver substance could be flatten by hitting it with a hammer, but it did not crack. Which two statements could be true?

2 answers:

melisa1 [442]3 years ago

8 0

Answer:

Explanation: A. The red substance was ionic.

C. The white substance was molecular.

melomori [17]3 years ago

6 0

Answer:

The red substance was ionic. The white substance was molecular.

Explanation:

B.C.

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Read the scenario and solve these two problems.

Burka [1]

Answers:

a) 5400000 J

b) 45.92 m

Explanation:

a) The kinetic energy $K$ of an object is given by:

$K=\frac{1}{2}mV^{2}$

Where:

$m=12000 kg$ is the mass of the train

$V=30 m/s$ is the speed of the train

Solving the equation:

$K=\frac{1}{2}(12000 kg)(30 m/s)^{2}$

$K=5400000 J$ This is the train's kinetic energy at its top speed

b) Now, according to the Conservation of Energy Law, the total initial energy is equal to the total final energy:

$E_{i}=E_{f}$

$K_{i}+P_{i}=K_{f}+P_{f}$

Where:

$K_{i}=5400000 J$ is the train's initial kinetic energy

$P_{i}=0 J$ is the train's initial potential energy

$K_{f}=0 J$ is the train's final kinetic energy

$P_{f}=mgh$ is the train's final potential energy, where $g=9.8 m/s^{2}$ is the acceleration due gravity and $h$ is the height.

Rewriting the equation with the given values:

$5400000 J=(12000 kg)(9.8 m/s^{2})h$

Finding $h$ :

$h=45.918 m \approx 45.92 m$

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Who was the last person to step on the moon?

Pavlova-9 [17]

Eugene Cernan was not the last, but he was the most recent.

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Which of the following combinations makes up an ionic compound?

Sonbull [250]

Answer:

D. A positive cation and a negative anion

Explanation:

An ionic compound is defined as the chemical compound formed by the combination of two charged particles or ions held together by electrostatic forces.

An ionic compound is made up of ions, a cation which is a positively charged ion and an anion which is a negatively charged ion. Example of ionic compounds are Lithium Fluoride, Lithium Iodide, and Sodium Bromide.

Hence, the correct answer is "D. A positive cation and a negative anion".

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3 years ago

When a battery is attached to an electrical circuit, the electrical energy produced comes from stored ___ energy.

Llana [10]

Answer:

Chemical energy

Explanation:

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A spring-loaded toy gun is used to shoot a ball of mass 1.5 kg straight up in the air, as shown. The spring has spring constant

asambeis [7]

Answer:

Part a)

U = 15.5 J

Part b)

h = 1.05 m

Part c)

v = 4.55 m/s

Explanation:

Part a)

Initial potential energy stored in the spring is given by

$U = \frac{1}{2}kx^2$

now we have

$k = 777 N/m$

x = 20.0 cm

now from above formula we will have

$U = \frac{1}{2}(777)(0.20)^2$

$U = 15.5 J$

Part b)

By mechanical energy conservation law we can say that initial spring potential energy stored = final gravitational potential energy at the top position

$\frac{1}{2}kx^2 = mgh$

$15.5 = 1.5(9.8)h$

$h = 1.05 m$

So maximum height from gun is 1.05 m

Part c)

For muzzle velocity of the ball we can use the energy conservation again

According to which the final kinetic energy of the ball = initial spring energy stored in it

$\frac{1}{2}mv^2 = \frac{1}{2}kx^2$

$(\frac{1}{2})(1.5 v^2) = 15.5$

$v = v = 4.55 m/s$

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3 years ago