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2 years ago

The Law of Conservation of Mass states that mass can be destroyed during a chemical change.

Physics

1 answer:

Vesna [10]2 years ago

5 0

The law of conservation of mass states that mass can be destroyed during a chemical change is TRUE

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You set your stationary bike on a high 80-N friction-like resistive force and cycle for 30 min at a speed of 8.0 m/s . Your body

stellarik [79]

A) The change in internal chemical energy is $1.15\cdot 10^7 J$

B) The time needed is 1 minute

Explanation:

First of all, we start by calculating the power output of you and the bike, given by:

$P=Fv$

where

F = 80 N is the force that must be applied in order to overcome friction and travel at constant speed

v = 8.0 m/s is the velocity

Substituting,

$P=(80)(8.0)=640 W$

The energy output is related to the power by the equation

$P=\frac{E}{t}$

where:

P = 640 W is the power output

E is the energy output

$t = 30 min \cdot 60 = 1800 s$ is the time elapsed

Solving for E,

$E=Pt=(640)(1800)=1.15\cdot 10^6 J$

Since the body is 10% efficient at converting chemical energy into mechanical work (which is the output energy), this means that the change in internal chemical energy is given by

$\Delta E = \frac{E}{0.10}=\frac{1.15\cdot 10^6}{0.10}=1.15\cdot 10^7 J$

From the previous part, we found that in a time of

t = 30 min

the amount of internal chemical energy converted is

$E=1.15\cdot 10^7 J$

Here we want to find the time t' needed to convert an amount of chemical energy of

$E'=3.8\cdot 10^5 J$

So we can setup the following proportion:

$\frac{t}{E}=\frac{t'}{E'}$

And solving for t',

$t'=\frac{E't}{E}=\frac{(3.8\cdot 10^5)(30)}{1.15\cdot 10^7}=1 min$

Learn more about power and energy:

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3 0

3 years ago

What is resonance frequency?

Bogdan [553]

A natural frequency of vibrations determined by the physical parameters of the vibrating object.

5 0

3 years ago

Read 2 more answers

If an electron is accelerated from rest through a potential difference of 1.60 x 102V, what is its de Broglie wavelength

Ivahew [28]

Answer:

0.09 x10^-10m

Explanation:

Using wavelength=( 12.27 A)/√V

= 12.27 x 10^-10/ √1.6x10^2

= 0.09x10^-10m

7 0

3 years ago

A volume variance is the difference between overhead at maximum production volume and that at the budgeted production volume.

umka21 [38]

The statement is not correct. Therefore, the answer is letter B. False. The actual definition of a volume variance is that it is the difference of the quantity consumed and the amount budgeted to be sold, the difference will furthermore be multiplied to the standard unit per price.

3 0

3 years ago

A boat crosses a 200m wide river at 3m/s, north relative to water. The river flows at 1m/s as shown. What is the velocity of the

Xelga [282]

Answer:

The resultant velocity = 3.16 m/s

Explanation:

Since the boat is moving North of the direction of the riverflow, the river would either be flowing westward or Eastward. The two motions form a right angle triangle with the resultant velocity being the hypotenuse of the traingle.

The resultant velocity will be given as ;

R² = B² + r²

Where B is the velocity of the boat and r is the velocity of the river

R² = 3² + 1²

R² = 10

R = √10 = 3.16 m/s

Therefore, the resultant velocity = 3.16 m/s

3 0

3 years ago