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nlexa [21]
4 years ago
13

Why are radio waves considered harmless while ultraviolet waves and x-rats considered harmful

Physics
1 answer:
Anvisha [2.4K]4 years ago
7 0
 They are usually thought as harmful.
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15) A 328-kg car moving at 19.1 m/s in the +x direction hits from behind a second car moving at 13 m/s in the same direction. If
kolbaska11 [484]

Answer:

Explanation:

Given that,

Mass of first car

M1= 328kg

The car is moving in positive direction of x axis with velocity

U1 = 19.1m/s

Velocity of second car

U2 = 13m/s, in the same direction as the first car..

Mass of second car

M2 = 790kg

Velocity of second car after collision

V2 = 15.1 m/s

Velocity of first car after collision

V1 =?

This is an elastic collision,

And using the conservation of momentum principle

Momentum before collision is equal to momentum after collision

P(before) = P(after)

M1•U1 + M2•U2 = M1•V1 + M2•V2

328 × 19.1 + 790 × 13 = 328 × V1 + 790 × 15.1

16534.8 = 328•V1 + 11929

328•V1 = 16534.8—11929

328•V1 = 4605.8

V1 = 4605.8/328

V1 = 14.04 m/s

The velocity of the first car after collision is 14.04 m/s

5 0
3 years ago
How many oxygen atoms are in Ca (NO3)2
Lapatulllka [165]

There are 6 atoms of oxygen in Ca (NO3)2.

5 0
3 years ago
What is the definition of force according to the Newton's first law of motion ​
Norma-Jean [14]

Answer:

In physics, a force is any influence that causes an object to undergo a certain change, either concerning its movement, direction, or geometrical construction. In other words, a force can cause an object with mass to change its velocity, i.e., to accelerate, or a flexible object to deform, or both.

Explanation:

4 0
3 years ago
A 20kg mass approaches a spring at a speed of 30 m/s. The mass compresses the spring 12cm before coming to a stop. Calculate the
Oksana_A [137]

Answer:

625000 N/ m

Explanation:

m= 20 kg

v= 30 m/s

x= 12 cm

k = ?

Here when the mass when hits at spring its speed is

Vi= 30 m/s

Finally it comes to rest after compressing for 12 cm

i-e Vf = 0 m/s

Distance= S= 12 cm = 0.12 m

using

2aS= Vf2 - Vi2

==> 2a ×0.12 = o- 30 × 30

==> a = 900 ÷ 0.24 = 3750 m/sec2

Now we know;

F = ma

F= -Kx

==> ma= -kx

==> 20 × 3750 = -K × 0.12

==> k = 625000 N/ m

5 0
3 years ago
How does quantum theory explain the emission spectra of atoms?
ankoles [38]
The correct answer is B.

Let us think of the classical theory first. In the classical theory, light is a wave that gives energy. This energy gradually helps the electron jump to a higher energy level.
In quantum theory, this is wrong; an electron cannot absorb a small amout of energy because there is not close enough state to jump to with that energy; only very specific amounts of energy lead to a change in orbital levels/ absorbance of energy. Also, each pair of energy levels has a specific energy difference that is needed from an electron so that it can move.
Hence, B is correct; all other sentences describe classical models of light-electron interactions

4 0
4 years ago
Read 2 more answers
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