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4 years ago

Alan wrote the following examples of changes in substance.

Physics

2 answers:

Anastaziya [24]4 years ago

6 0

Answer:

The correct option is B

Explanation:

A physical change is characterized by the following

no new substance is formed
easily reversible
cannot be represented by a chemical reaction

A chemical change is characterized by the following

new substances are formed
easily reversible
can be represented by a chemical reaction

A camp fire is usually made by burning woods. This process is called combustion, it involves the burning of a substance in oxygen to produce carbon dioxide (CO₂). This is a chemical change because new substance (CO₂) is formed and the ashes formed (after burning) cannot be reversed back to wood.

Plants convert carbon dioxide and water into glucose and oxygen through photosynthesis. This process is also a chemical change because new substances (glucose and oxygen) are formed and the reaction cannot also be easily reversed.

The reaction involved can be represented as

6CO₂ + 6H₂O ⇒ C₆H₁₂O₆ + 6O₂

Yuliya22 [10]4 years ago

5 0

A campfire being lighted and plants converting carbon-dioxide and water into glucose and oxygen are both forms of chemical change.

Therefore, the answer is:

B. Both are examples of chemical change.

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How should Tika most likely describe this relationship between force and distance to her study group

omeli [17]

Answer:

Force is work done divided by distance

Explanation:

Work done to an object is given as rhe product of force and diatance moved, hence expressed as W=Fd where F is the applied force in Newtons, d is diatance moved in meters and W is work. The relationship between force and distance then is found by making either F or d the subject hence

$F=\frac {W}{d}\\d=\frac {W}{F}$

hence we can say that distance is given by dividing work by force or alternatively Force is relates to distance by dividing work done by distance. Both are correct.

7 0

3 years ago

Read 2 more answers

A 4.04 kg block slides down a smooth, frictionless plane having an inclination of 30◦. The acceleration of gravity is 9.8 m/s^2.

aleksandrvk [35]

Answer:

Explanation:

What a lot of words to solve such a simple problem! The perpendicular force is the one that is pushing straight down on the plane. There is no side to side movement here or friction acting on this dimension at all. Perpendicular force is the same as the weight of the block. That's it! Perpendicular force is also normal force which is the same thing as weight:

w = mg so

w = (4.04)(9.8) and

w = 4.0 × 10¹ N

5 0

3 years ago

The size of a balloon increases when the pressure inside it increases. The balloon gets bigger when it is left in the heat from

Masteriza [31]

Explanation:

This happens because the gas inside tend to expand because its temperature gets higher.

This is why the balloon that is put in a freezer for too long tend to gets smaller, because the gas temperature that is inside the balloon decreases.

(you can try it at home)

It is related to the temperature of the gas.

5 0

3 years ago

During your summer internship for an aerospace company, you are asked to design a small research rocket. The rocket is to be lau

Thepotemich [5.8K]

Answer:

$T=6.75s$

Explanation:

We must separate the motion into two parts, the first when the rocket's engines is on and the second when the rocket's engines is off. So, we need to know the height ( $h_1$ ) that the rocket reaches while its engine is on and we need to know the distance ( $h_2$ ) that it travels while its engine is off.

For solving this we use the kinematic equations:

In the first part we have:

$h_1=v_0T+\frac{1}{2}aT^2\\h_1=0*T+\frac{1}{2}(16\frac{m}{s^2})T^2\\h_1=8\frac{m}{s^2}T^2\\$

and the final speed is:

$v_f=v_0+aT\\v_f=0+16\frac{m}{s^2}T\\v_f=16\frac{m}{s^2}T$

In the second part, the final speed of the first part it will be the initial speed, and the final speed is zero, since gravity slows it down the rocket.

So, we have:

$v_f^2=v_0^2+2gh_2\\2gh_2=v_f^2-v_0^2\\h_2=\frac{v_f^2-v_0^2}{2g}\\h_2=\frac{0^2-(16\frac{m}{s^2}T)^2}{2(-9.8\frac{m}{s^2})}\\h_2=\frac{-256\frac{m^2}{s^4}T^2}{-19.6\frac{m}{s^2}}\\h_2=13.06\frac{m}{s^2}T^2$

The sum of these heights will give us the total height, which is known:

$h=h_1+h_2\\960m=8\frac{m}{s^2}T^2+13.06\frac{m}{s^2}T^2\\960m=21.06\frac{m}{s^2}T^2\\T^2=\frac{960m}{21.06\frac{m}{s^2}}\\T^2=45.58s^2\\T=\sqrt{45.58s^2}\\T=6.75s$

This is the time that its needed in order for the rocket to reach the required altitude.

5 0

3 years ago

How long was a 50 W lightbulb left on for if 500,002 J were burned?

saveliy_v [14]

" 50 W " means " 50 Watts " or " 50 Joules per second ".

(500,002 J) / (50 J/sec) = <em>10,000.04 seconds</em>

(That's 2 hours 46 minutes 40.04 seconds.)

3 0

3 years ago