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4 years ago

Why are some electromagnetic waves harmful to you but others are not?

2 answers:

8 0

Because for example a lightning bolt is an electromagnetic wave. Lighting bolts can hurt you or even kill you. But others waves cant harm you.
Hope this helps

Rudiy274 years ago

3 0

Answer
They have different frequencies.

Explanations
Some electromagnetic wave have high frequency than others. hose with high frequency are more harmful than those with low frequency.

Waves with high frequency have a higher penetrating power and they can kill cells if exposed to it. This makes them harmful.

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A plane drops a hamper of medical supplies from a height of 5000 m during a practice run over the ocean. The plane’s horizontal

Marizza181 [45]

Answer:

346.70015 m/s

Explanation:

In the x axis speed is

$v_x=149\ m/s$

In the y axis

$v_y=\sqrt{2gh}\\\Rightarrow v_y=\sqrt{2\times 9.8\times 5000}$

The resultant velocity is given by

$v=\sqrt{v_x^2+v_y^2}\\\Rightarrow v=\sqrt{149^2+2\times 9.8\times 5000}\\\Rightarrow v=346.70015\ m/s$

The magnitude of the overall velocity of the hamper at the instant it strikes the surface of the ocean is 346.70015 m/s

4 0

3 years ago

Please help

Allisa [31]

We are given:

Mass of the rocket = 10 kg

Weight of the Rocket = 100 N

Upward thrust applied by the rocket = 400 N

Net upward force on the rocket:

We are given that gravity pulls the rocket with a force of 100 N

Also, the rocket applied a force of 400N against gravity

Net upward force = Upward thrust - Force applied by gravity

Net upward force = 400 - 100

Net upward force = 300 N

Upward Acceleration of the Rocket:

From newton's second law:

F = ma

replacing the variables

300 = 10 * a

a = 30 m/s²

5 0

3 years ago

A wire of length 5mm and Diameter 2m extends by 0.25 when a force of 50N was use. calculate the

bazaltina [42]

Answer and Explanation:

Data provided in the question

Force = 50N

Length = 5mm

diameter = 2.0m = $2\times 10^{-3}$

Extended by = 0.25mm = $0.25\times 10^{-3}$

Based on the above information, the calculation is as follows

a. The Stress of the wire is

$= \frac{force\ applied}{area\ of \ circle}$

here area of circle = perpendicular to the are i.e cross-sectional i.e

= $\frac{\pi d^{2}}{4}$

= $\frac{\pi(2\times 10^{-3})^2}{4}$

Now place these above values to the above formula

$= \frac{4\times 50}{\pi\times 4 \times 10^{-6}} \\\\ = \frac{50}{\pi}$

= 15.92 MPa

As 1Pa = 1 by N m^2

So,

MPa = 10^6 N m^2

b. Now the strain of the wire is

$= \frac{Change\ in\ length}{initial\ length} \\\\ = \frac{0.25\times 10^{-3}}{5}$

= $5 \times 10^{-5}$

3 0

4 years ago

If a cart goes around a turn at 20 km/h ,what remains constant

Vitek1552 [10]

Answer: 4.speed

Explanation:

In this case, we know that the cart remains at a constant 20km/h.

Now, one could say that "the velocity remains constant, because it always is 20km/h"

But remember that velocity is a vector, so this has a direction, and if the cart is going around a turn, then the direction of motion is changing, which tell us that there is acceleration.

But the module of the velocity, the speed, remains constant at 20km/h.

Then the correct option is 4, speed.

7 0

3 years ago

Which of the following best describes the term thermal energy? Choose one: A. The energy of an object in motion due to its mass

o-na [289]

Answer:

The correct option is (d).

Explanation:

The energy a particle has because of its charge and its position relative to another particle is called thermal energy.
It is the energy that comes from heat. This is generated by the movement of the particles in an object.
Thermal energy is the energy an object or system has due to the movement of particles within.

Hence, the correct option is (d).

8 0

3 years ago