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3 years ago

Wood is burning. *

Physics

1 answer:

xenn [34]3 years ago

5 0

Answer:

It may seem as though burning destroys matter, but the same amount, or mass, of matter still exists after a campfire as before. Look at Figure 3.7.1 below. It shows that when wood burns, it combines with oxygen and changes not only to ashes, but also to carbon dioxide and water vapor. The gases float off into the air, leaving behind just the ashes. Suppose you had measured the mass of the wood before it burned and the mass of the ashes after it burned. Also suppose you had been able to measure the oxygen used by the fire and the gases produced by the fire. What would you find? The total mass of matter after the fire would be the same as the total mass of matter before the fire.

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Which of the following is an example of an allocation decision?|

Oksana_A [137]

Answer:

The answer is D- Coal is set aside to burn as heating fuel

Explanation:

Allocation decisions set aside resources for a specific purpose.

7 0

4 years ago

Read 2 more answers

a stone is thrown horizonttaly from a cliff of a hill with an initial velocity of 30m/s it hits the ground at a horizontal dista

ELEN [110]

Answer:

a) Time = 2.67 s

b) Height = 35.0 m

Explanation:

a) The time of flight can be found using the following equation:

$x_{f} = x_{0} + v_{0_{x}}t + \frac{1}{2}at^{2}$ (1)

Where:

$x_{f}$ : is the final position in the horizontal direction = 80 m

$x_{0}$ : is the initial position in the horizontal direction = 0

$v_{0_{x}}$ : is the initial velocity in the horizontal direction = 30 m/s

a: is the acceleration in the horizontal direction = 0 (the stone is only accelerated by gravity)

t: is the time =?

By entering the above values into equation (1) and solving for "t", we can find the time of flight of the stone:

$t = \frac{x_{f}}{v_{0}} = \frac{80 m}{30 m/s} = 2.67 s$

b) The height of the hill is given by:

$y_{f} = y_{0} + v_{0_{y}}t - \frac{1}{2}gt^{2}$

Where:

$y_{f}$ : is the final position in the vertical direction = 0

$y_{0}$ : is the initial position in the vertical direction =?

$v_{0_{y}}$ : is the initial velocity in the vertical direction =0 (the stone is thrown horizontally)

g: is the acceleration due to gravity = 9.81 m/s²

Hence, the height of the hill is:

$y_{0} = \frac{1}{2}gt^{2} = \frac{1}{2}9.81 m/s^{2}*(2.67 s)^{2} = 35.0 m$

I hope it helps you!

5 0

3 years ago

To produce a magnetic field, What does an electromagnet require?

kodGreya [7K]

Selection D makes most sense

8 0

3 years ago

Read 2 more answers

Si aplicamos una fuerza constante de 30 N sobre un cuerpo de 25 Kg, este se mueve de tal manera que en 5 s adquiere la velocidad

Ganezh [65]

Answer:

<em>Si hay rozamiento y el valor de la fuerza de roce es 10 N</em>

Explanation:

<u>Fuerza Neta</u>

La fuerza neta sobre un cuerpo es la suma vectorial de todas las fuerzas actuantes sobre el mismo.

Si conocemos el módulo de la fuerza neta F y la masa m del cuerpo, aplicamos la segunda ley de Newton para relacionarlas con la aceleración a:

$F=m.a$

Tenemos los datos cinemáticos de la situación, según la cual el cuerpo adquiere una velocidad (desde el reposo) de 4 m/s en 5 s.

Utilizamos la fórmula:

$v_f=v_o+a.t$

Y despejamos la aceleración:

$\displaystyle a=\frac{v_f-v_o}{t}$

$\displaystyle a=\frac{4-0}{5}$

$a=0.8 \ m/s^2$

Podemos calcular la aceleración real que el cuerpo adquiere, producto de una fuerza efectiva igual a:

$F_e=25\ Kg\cdot 0.8 \ m/s^2$

$F_e=20\ N$

Si se está aplicando una fuerza de $F_a= 30 N$ y solo 20 N producen movimiento, entonces se está perdiendo en rozamiento una fuerza:

$F_r=F_a-F_e=30 - 20=10$

$F_r=10\ N$

Si hay rozamiento y el valor de la fuerza de roce es 10 N

8 0

3 years ago

A wooden block with mass 1.60 kg is placed against a compressed spring at the bottom of a slope inclined at an angle of 30.0° (p

andreyandreev [35.5K]

Answer:

The amount of potential energy that was initially stored in the spring is 88.8 J.

Explanation:

Given that,

Mass of block = 1.60 kg

Angle = 30.0°

Distance = 6.55 m

Speed = 7.50 m/s

Coefficient of kinetic friction = 0.50

We need to calculate the amount of potential energy

Using formula of conservation of energy between point A and B

$U_{A}+k_{A}+w_{A}=U_{B}+k_{B}$

$U_{A}+0-fd=mgy+\dfrac{1}{2}mv^2$

$U_{A}=\mu mg\cos\theta\times d+mg h\sin\theta+\dfrac{1}{2}mv^2$

Put the value into the formula

$U_{A}=0.50\times1.60\times9.8\cos30\times6.55+1.60\times9.8\times6.55\sin30+\dfrac{1}{2}\times1.60\times(7.50)^2$

$U_{A}=88.8\ J$

Hence, The amount of potential energy that was initially stored in the spring is 88.8 J.

7 0

3 years ago