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Eddi Din [679]
3 years ago
6

Electromagnetic waves can transfer energy without a(n)

Physics
1 answer:
Anna71 [15]3 years ago
7 0
Some waves can travel without a -medium-, a channel like telephone power lines, lenses, or even particles in the air or in water.
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The strength of an electromagnet can be altered by
denpristay [2]
The strength of an electromagnet can be altered by increasing the number of coils around the core. The more times the coil is wrapped, the stronger the electromagnet is.

Your answer is: B) Increasing the number of coils around the core 

Have an amazing day and stay hopeful!

3 0
3 years ago
Read 2 more answers
Will mark as BRAINLIEST.....
Jlenok [28]

Answer: initially the packet was ascending up with the balloon.

Taking upward as positive direction;

initial velocity, u = 4.9 m/s

final velocity = v m/s

initial height, h₁ = 245 m  

final height, h₂ = 0

a = -9.8 m/s²

time taken = t seconds

s = ut + 0.5at²

⇒ (h₂-h₁) = ut + 0.5at²

⇒ 0-245 = 4.9t + 0.5×(-9.8)×t²

⇒ -245 = 4.9t - 4.9t²

⇒ 4.9t² -4.9t -245 =0

Solving it, we get  t = 7.59s

v = u + at = 4.9 -9.8×7.59 = 4.9 - 74.38 = -69.48 m/s

So velocity is 69.48 m/s downward

Explanation:

5 0
4 years ago
A 60 kg skydiver is falling at a terminal velocity of 50 m/s.
marishachu [46]

Answer:

The gravitational force is definitely acting downwards towards the ground and this is equal to the weight of the skydiver.

the acceleration a = 7.8 m/s²

Explanation:

Given that :

the mass of the skydiver = 60 kg

Velocity = 50 m/s

Thus;  gravitational force is definitely acting downwards towards the ground and this is equal to the weight of the skydiver.

Also; the air resistance is acting upward and the resultant of both forces = mass×acceleration

So;

mg-R = ma

60(9.8) - 120 = 60(a)

588 -120 = 60a

468 = 60a

a = \frac{468}{60}

a = 7.8 m/s²

Hence, the acceleration a = 7.8 m/s²

5 0
3 years ago
How much time does it take for a car traveling 19.1 m/s to cover a distance of 1200 m?
nalin [4]

Answer:

63

Explanation:

it would take around 63 if ur asking for 1200/19.1

4 0
3 years ago
Electricity from the local power company costs 5.79 cents/kWh. How much would it cost to run a 120-W stereo system for 4.0 hours
xenn [34]

Answer:

<em>Answer: B. $0.78.</em>

Explanation:

<u>Cost of Electricity </u>

The rate of the cost of electricity is usually expressed in $/kWh or cents/kWh because the consumption of electricity is measured in Kilowatts-hour.

The local power company charges 5.79 cents/kWh.

We are required to calculate the cost to run a 120 W stereo system for 4 hours per day for 4 weeks.

The total consumption time is 4 hours/day * 7 days/week *4 weeks = 112 hours

The total energy consumed is 120 W * 112 h =13,440 Wh.

Converting to kWh: 13,440 Wh/1,000 = 13.440 kWh.

Finally, we multiply by the cost rate: 5.79 cents/kWh * 13.440 kWh = 77.8 cents/100 = $0.78.

Answer: B. $0.78.

3 0
3 years ago
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