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laila [671]
2 years ago
15

Which of the following statements is true of electromagnetic waves but NOT mechanical waves.

Physics
1 answer:
Neko [114]2 years ago
4 0

Answer:

a

Explanation:

what the heck is a medium

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In countries where there is very hot and very cold weather, should the gaps between the lengths of railway track be wider or nar
kipiarov [429]
They should be bigger as if it is hot the tracks will expand as it is made of metal and then there is more room for it to expand or contract
5 0
3 years ago
2. What is the feather's initial velocity (before it is dropped) in m/s?
Dmitrij [34]

Answer: 0

Explanation: Initial velocity is 0.

7 0
3 years ago
A wire is made from a material having a temperature coefficient of resistivity of 0.0003125 (°C^-1). In an experiment, we mainta
beks73 [17]

Answer:

The power decreases by 36%

Explanation:

Given:

At 20° C

Power, P₀ = 300 W

Potential difference, V = 150 volts

Now, power is given as

P = V²/R

where, R is the resistance

on substituting the values, we get

300 = 150²/R₀

or

R₀ = 75 Ω

Now, the variation of resistance with temperature is given as

R = R₀[1 + α(T - T₀)]

where, α is the temperature coefficient of resistivity = 0.0003125 (°C⁻¹)

now, at

T₀ = 20° C

R₀ = 75 Ω

for

T = 1820° C

we have

R = R₀[1 + α(T - T₀)]

substituting the values

we get

R = 75×[1 + 0.0003125 × (1820 - 20)]

or

R = 117.18 Ω

Now using the formula for power

We have,

P = V²/R

or

P = 150²/117.18 = 192 W

Therefore, the percentage change will be

= \frac{P-P_0}{P_0}\times 100

on substituting the values , we get

= \frac{192-300}{300}\times 100

= -36%

here, negative sign depicts the decrease in power

3 0
3 years ago
Read 2 more answers
A stone was dropped off a cliff and hit the ground with a speed of 96 ft/s. What is the height of the cliff? (Use 32 ft/s2 for t
nadezda [96]
The initial velocity of the stone is 0 ft/s. Given the initial velocity (Vi), final velocity (Vf), and acceleration due to gravity (g), the distance may be calculated through the equation,
                                     d = ((Vf)² - (Vi)²) / 2g
Substituting the known values,
                                     d = ((96 ft/s)² - 0))/ (2x32.2)
The value of d is 143.10 ft. 
4 0
3 years ago
Does the ke of a car change more when it accelerates from 11 km/h to 21 km/h or when it accelerates from 21 km/h to 31 km/h?
svp [43]
Titty milk I think because it taste amazing so you can go 21km/h
7 0
3 years ago
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