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4 years ago

Which of the following statements about electromagnetic and mechanical waves is true?

Chemistry

1 answer:

mr Goodwill [35]4 years ago

4 0

Answer:

B. Mechanical waves must travel through a medium, but electromagnetic waves do not require a medium.

Explanation:

A wave is defined as any disturbance that transmits energy from one point to another.

Waves can be typically classified as either mechanical or electromagnetic waves.

Mechanical waves are waves that requires a medium for their propagation. In a vacuum, they cannot be propagated and would not cause any disturbance. An example is sound waves.

Electromagnetic waves do not require a medium to be propagated. They can pass through any substance in nature. Electromagnetic radiations belongs to this class.

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Which elements are out of order in terms of atomic mass. co,Ni or Li,be or I,xe

valkas [14]

Answer:

The pair co,Ni is out of order in terms of atomic mass

Explanation:

For co,Ni

Atomic mass of Co = 58.9331 u

Atomic mass of Ni = 58.6934

For Li,be

Atomic mass of Li = 6.941 u

Atomic mass of be = 9.012182 u

For I,xe

Atomic mass of I = 126.90447 u

Atomic mass of Xe = 131.293 u

Hence, the pair co,Ni is out of order in terms of atomic mass

7 0

3 years ago

20 N force moving a box to 30 meters distance. How much work id done? if it takes 10 sec to do this work, how much power is used

dalvyx [7]

Answer:

Work done = 600 J

Power used = 60 W

Explanation:

Given:

Force acting on the box is, $F=20\ N$

Displacement of the box is, $S=30\ m$

Time taken for the work, $t=10\ s$

Now, we know that, work is said to be done by a force only when there is displacement caused by the force in its direction.

Here, the force acting on the box causes a displacement of 30 m in its direction. So, work done is equal to the product of force and displacement caused.

Therefore, work done on the box is given as:

$Work=Force\times Displacement\\Work=F\times S\\Work=(20\ N)\times (30\ m)\\Work=600\ J$

Therefore, the work done is 600 J.

Now, we know that, power is given as work done per unit time.

So, power used is given as:

$Power=\frac{Work}{Time}\\\\Power=\frac{600\ J}{10\ s}\\\\Power=60\ W$

Therefore, the power used is 60 W.

5 0

3 years ago

A Snickers bar contains 27.0 g of sugars (carbohydrates), 4.0 g of protein and 12.0 g of fat. How many food calories (Cal) are c

amm1812

Answer:

There are 232 calories in the bar

Explanation:

Carbohydrates and protein are both 4 calories per gram, while fat is 9 calories per gram.

$27*4=108\\4*4=16\\12*9=108\\108+108+16=232$

4 0

3 years ago

Which is the metric standard for measuring energy? Which unit is used for specific heat capacity? If you wanted to compare the a

DENIUS [597]

1. Which is the metric standard for measuring energy?

The metric standard for measuring of energy defined by the International System of Units is the joule (J), which is defined as the work done by a force of a newton in a displacement of one meter in the direction of force. So,

1 J = 1 N m = 1 kg·m²/s²

Calorie is also frequently used in scientific and technological applications. Calorie is a unit of thermal energy that is equivalent to the amount of heat needed to raise the temperature of 1 gram of water by 1 degree Celsius.

1 cal = 4,184 J

2. Which unit is used for specific heat capacity?

The specific heat capacity (c) is a physical quantity that is defined as the amount of heat (q) that must be supplied to the mass unit of a thermodynamic substance or system to raise its temperature by one unit. So,

c = q / m ΔT

where m is the mass of the substance and ΔT is the temperature increase.

In this way, as heat is a form of energy, the International System of Units expresses the specific heat in joules per kilogram and per kelvin (J kg⁻¹ K⁻¹). Another common unit, not belonging to the SI, is the calorie per gram and per degree centigrade (cal g⁻¹ ° C⁻¹).

3. If you wanted to compare the abilities of olive oil and peanut oil to gain or lose thermal energy, which unit would you use?

You should use units of specific heat capacity (J kg⁻¹ K⁻¹) since, as mentioned above, this is a physical quantity that measures the amount of heat that must be supplied to an specific mass of a substance or system to raise its temperature.

Heat is a thermal energy, so by using heat capacity units you can compare the ability of olive oil and peanut oil to gain or lose thermal energy by varying its temperature.

3 0

3 years ago

Read 2 more answers

Olympic cyclists fill their tires with helium to make them lighter. Assume that the volume of the tire is 860 mL , that it is fi

nata0808 [166]

Answer:

a) the mass of air = 8.24 grams

b) the mass of helium = 1.14 grams

c) the mass difference = 7.10 grams

Explanation:

Step 1: Data given

Volume of the tire = 860 mL

Total pressure = 120 psi

Temperature = 26°C

molar mass of air = 28.8 g/mol

Step 2: Convert psi to atm

(

120 psi) (1 atm / 14.7 psi) = 8.163

Step 4: Calculate moles

PV = nRT

⇒ with P = the pressure = 8.163 atm

⇒ with V = the volume = 860 mL = 0.860 L

⇒ with n = the number of moles = TO BE DETERMINED

⇒ with R = the universal gas constant = 0.08206 L*atm/K*mol

⇒ with T = the temperature = 26 °C = 299 Kelvin

n = (8163*0.860)/(0.08206*299)

n = 0.2861 moles of gas

Step 5: Calculate the mass of air in an air-filled tire.

Mass = moles * molar mass

Mass = (0.2861 moles of gas) (28.8 g/mol)

Mass = 8.24 grams

Step 6: Calculate the mass of helium in a helium- filled tire.

mass of helium = 0.2861 moles of gas * 4 g/mol)

mass of helium = 1.14 grams

Step 7: What is the mass difference between the two?

Δmass= 8.24 grams - 1.14 grams

Δmass= 7.10 grams

8 0

4 years ago