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1 year ago

a college student produces about 100 kcal of heat per hour on the average what is the rate of energy production and joules

Physics

1 answer:

Bond [772]1 year ago

6 0

Given:

Amount of heat produced = 100 kcal per hour

Let's find the rate of energy production in joules.

We know that:

1 calorie = 4.184 Joules

1 kcal = 4.184 Joules

To find the rate of energy production in Joules, we have:

$\begin{gathered} Rate=100\ast4.184 \\ \\ \text{Rate}=418.4\text{ KJ/hour} \end{gathered}$

Therefore, the rate of energy production in joules is 418.4 kJ/h which is equivalent to 418400 Joules

ANSWER:

418.4 kJ/h

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Suppose that the speed of light in a vacuum were one million times smaller than its actual value: c = 3.00 × 10^2 m/s. The sprin

Mama L [17]

Answer:

The distance is $5.4\times10^{-2}\ m$ .

Explanation:

Given that,

Spring constant = 670 N/m

Mass = 0.011 g

We know that,

The potential energy stored in a compressed spring is given by

$E=\dfrac{1}{2}kx^2$ ....(I)

We know that,

The equation of energy is

$E = mc^2$ ....(II)

We need to calculate the distance

Using equation (I) and (II)

$mc^2=\dfrac{1}{2}kx^2$

$x^2=\dfrac{2mc^2}{k}$

Where, m = mass

c = speed of light

k = spring constant

Put the value into the formula

$x^2=\dfrac{2\times0.011\times10^{-3}\times(3\times10^{2})^2}{670}$

$x=\sqrt{0.002955}$

$x=0.054$

$x=5.4\times10^{-2}\ m$

Hence, The distance is $5.4\times10^{-2}\ m$ .

5 0

3 years ago

A 12.0 V battery is connected into a series circuit containing a 12.0 Ω resistor and a 3.50 H inductor. (a) In what time interva

oksano4ka [1.4K]

The first half of my answer is just to derive a result which you can then choose to memorize for future reference.

Applying Kirchhoff's loop rule stating that the circuit's voltage gains/drops sum to 0:

ΣV = 0

When we have a direct current resistor-inductor circuit where a battery, resistor, and inductor are connected in series, we have the following voltage values for each component as listed below. Positive values indicate a voltage gain and negative values indicate a voltage drop:

Battery: +ℰ
Resistor: -iR, where i is the current and R is the resistance
Inductor: -L(di/dt), where L is the inductance and di/dt is the rate of change of the current over time (first derivative of current with respect to time t)

Sum up these voltage changes and set the sum equal to 0 as per Kirchhoff's loop rule:

ℰ - iR - L(di/dt) = 0

What we have here is a first-order differential equation because we have the above equation in terms of current as a function of time as well as its first derivative with respect to time. What we want to do is find a current function that both satisfies the differential equation as well as the initial condition that the current at t = 0s is zero, because we have just inserted the battery and are waiting for the current through the circuit to build up.

Actually finding such a current function requires you to have taken at least an introductory class on differential equations... or access to the Wolfram|Alpha differential equation solver. Since the rest of the derivation is all mathematics, I will take you straight to the result.

The current function i(t) that satisfies both the differential equation above as well as the initial condition that i(0) = 0 is given by:

i(t) = (-ℰ/R) $e^{-Rt/L}$ + ℰ/R

We know that the inductor will oppose the change in current, but as time goes on this opposition decreases closer and closer to 0. To find the maximum current, we simply calculate:

$\lim_{t \to \infty} i(t)$ = ℰ/R

The maximum current is simply the battery's terminal voltage divided by the resistor's resistance.

Now we calculate when the circuit reaches 50.0% of the maximum current, i.e. the time t for which i = ℰ/(2R)

This is easy algebra from here on to the end:

i(t) = (-ℰ/R) $e^{\frac{-Rt}{L}}$ +ℰ/R = ℰ/(2R)

$-e^{\frac{-Rt}{L}}$ + 1 = 1/2

$e^{\frac{-Rt}{L}}$ = 1/2

-Rt/L = ㏑(1/2)

t = (-L/R)㏑(1/2)

Substitute our given values for L and R:

L = 3.50H, R = 12.0Ω

Therefore, the circuit will reach half of its maximum current at 0.202 seconds.

6 0

3 years ago

a young child standing in the aisle of a parked bus tosses a ball straight up in the air and lets it drop at her feet. If instea

Shalnov [3]

When the bus was at rest the ball landed at the child's feet.

Now, when the bus is moving at a constant velocity and the ball will again land at the child's feet

Reason:

The relative velocity of the child and the ball with respect of the bus is zero because they both are part of the same bus and are moving with the bus with same speed and in the same direction. Hence, There is no horizontal velocity of the ball with respect to the child. So, the ball will go vertically up with respect to the child and will land at the child's feet.

3 0

3 years ago

What does the 2 mean in the formula 5Mg3(PO4)2?

anastassius [24]

Answer: There is two (PO4) in the formula

Explanation:

Just be aware of the difference between numbers to the right and left: 5Mg3 means there are a total of 5 Mg (if 3 is a number in the bottom left) the 3 in (PO4) means there are 3 PO4 but because of the 2 it could mean there are 6.

Depends if the elements are separated

8 0

3 years ago

Cl has an atomic number of 17 and an atomic mass of 35. How many

lubasha [3.4K]

Answer:

7 Electrons

Explanation:

Assuming that final energy level is that same as valence shell, we first need to find how many of the electrics will be used to fill the ones before it.

Electron shell capacities are as follows :

First shell/Ebergy level: 2 electrons

Seconds shell/energy level : 8 electrons

Third shell /energy level :8 electrons

The first two shells total to 10, and the first three shells total to 18. Since chlorine (17) fills more than 2 shells but less that 3, the third one is its final energy level. We find the number in the final energy level by subtracting the 10 in the full first two. 2+8=10

17-10=7

Chlorine has 7 electrons on its final energy level.

Hope this helped!

3 0

3 years ago