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4 years ago

How much physical activity do adults need

1 answer:

5 0

For most healthy adults, the Department of Health and Human Services recommends these exercise guidelines: Aerobic activity. Get at least 150 minutes a week of moderate aerobic activity or 75 minutes a week of vigorous aerobic activity. You also can do a combination of moderate and vigorous activity.

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Use the SI prefixes in Table 3 of this chapter to convert these hypothetical units of measure into appropriate quantities: a. 10

Amanda [17]

The first response would be "deca," since this is a multiple of 10^1. B, since it's working off the thousands prefix (10^3), would be "kilo." The third, at 10^-6, would be "micro." Next, at 10^-9, would be "nano," and the final, 10^18, would have a prefix of "exa."

6 0

3 years ago

A college student is working on her physics homework in her dorm room. her room contains a total of 6.0×1026 gas molecules. as s

ella [17]

6.6 degrees C Let's model the student as a 125 w furnace that's been operating for 11 minutes. So 125 w * 11 min = 125 kg*m^2/s^3 * 11 min * 60 s/min = 82500 kg*m^2/s^2 = 82500 Joule So the average kinetic energy increase of each gas molecule is 82500 J / 6.0x10^26 = 1.38x10^-22 J Now the equation that relates kinetic energy to temperature is: E = (3/2)Kb*Tk E = average kinetic energy of the gas particles Kb = Boltzmann constant (1.3806504Ă—10^-23 J/K) Tk = Kinetic temperature in Kelvins Notice the the energy level of the gas particles is linear with respect to temperature. So we don't care what the original temperature is, we just need to know by how much the average energy of the gas particles has increased by. So let's substitute the known values and solve for Tk E = (3/2)Kb*Tk 1.38x10^-22 J = (3/2)1.3806504Ă—10^-23 J/K * Tk 1.38x10^-22 J = 2.0709756x10^-23 J/K * Tk 6.64 K = Tk Rounding to 2 significant digits gives 6.6K. So the temperature in the room will increase by 6.6 degrees K or 6.6 degrees C, or 11.9 degrees F.

7 0

3 years ago

On being introduced to the laws of thermodynamics, a student retorted, “When the brakes of a moving car are applied, the kinetic

inn [45]

Answer:

No, not at all. This kinetic energy of car is converted/lost in the form of sound and heat under the tyre when driver apply brakes.

Explanation:

This law states that energy can neither be created nor destroyed but it changes from one form to the other.

In this case reduction of kinetic energy of car does not contradict the law but it changes into heat and sound energy. When driver apply brakes we hear the sound of Tyre due to friction with the road. The tyre become hot too.

So it is not in contradiction to the law of conservation of energy (First Law of Thermodynamics).

Please mark branliest if you are satisfied with the answer. Thanking you in anticipation.

5 0

3 years ago

A 2.0-kilogram mass is located 3.0 meters above

leva [86]

The correct answer is: Option (3) 9.8 N/kg

Explanation:

According to Newton's Law of Gravitation:

$F_g = \frac{GmM}{R^2}$ --- (1)

Where G = Gravitational constant = 6.67408 × 10⁻¹¹ m³ kg⁻¹ s⁻²

m = Mass of the body = 2 kg

M = Mass of the Earth = 5.972 × 10²⁴ kg

R = Distance of the object from the center of the Earth = Radius of the Earth + Object's distance from the surface of the Earth = (6371 * 10³) + 3.0 = 6371003 m

Plug in the values in (1):

(1)=> $F_g = \frac{6.67408 * 10^{-11} * 2 * 5.972*10^{24}}{(6371003)^2} = 19.63$

Now that we have force strength at the location, we can use:

Force = mass * gravitational-field-strength

Plug in the values:

19.63 = 2.0 * gravitational-field-strength

gravitational-field-strength = 19.63/2 = 9.82 N/kg

Hence the correct answer is Option (3) 9.8 N/kg

4 0

3 years ago

Read 2 more answers

Find A and effective resistance. (Ill give Brainliest if you provide explaination)

Alex777 [14]

Answer:

A = 2.4 A

$R_{eq} = 5 \ \Omega$

Explanation:

The voltage in the circuit, V = 12 V

The given circuit shows four resistors with R₁ and R₂ arranged in series with both in parallel to R₃ and R₄ which are is series to each other

R₁ = 4 Ω

R₂ = 6 Ω

R₄ = 5 Ω

The voltage across R₃ = 6 V

Voltage across parallel resistors are equal, therefore;

The total voltage across R₃ and R₄ = 12 V

The total voltage across R₁ and R₂ = 12 V

The voltage across R₃ + The voltage across R₄ = 12 V

∴ The voltage across R₄ = 12 V - 6 V = 6 V

The current flowing through R₄ = 6V/(5 Ω) = 1.2 A

The current flowing through R₃ = The current flowing through R₄ = 1.2 A

The resistor, R₃ = 6 V/1.2 A = 5 Ω

Therefore, we have;

The sum of resistors in series are R₁ + R₂ and R₃ + R₄, which gives;

$R_{series \, 1}$ = R₁ + R₂ = 4 Ω + 6 Ω = 10 Ω

$R_{series \, 2}$ = R₃ + R₄ = 5 Ω + 5 Ω = 10 Ω

The sum of the resistors in parallel is given as follows;

$\dfrac{1}{R_{eq}} = \dfrac{1}{R_{series \, 1}} + \dfrac{1}{R_{series \, 2}} = \dfrac{R_{series \, 2} + R_{series \, 1}}{R_{series \, 1} \times R_{series \, 2}}$

Therefore;

$R_{eq} = \dfrac{R_{series \, 1} \times R_{series \, 2}}{R_{series \, 1} + R_{series \, 2}}$

Therefore;

$R_{eq} = \dfrac{10\times 10}{10 + 10} \ \Omega = 5 \ \Omega$

$R_{eq} = 5 \ \Omega$

The value of the current, A, in the circuit, I = V/ $R_{eq}$

A = I = 12 V/(5 Ω) = 2.4 A

A = 2.4 A

3 0

3 years ago