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densk [106]
4 years ago
14

23) A high school website directs parents to not allow student access to blue laser pointers or allow the students to bring them

to school. It includes a video describing the danger inherent in the misuse of all laser pointers particularly the blue laser pointer. Why would they claim that blue laser pointers are more of a concern than red laser pointers?
Physics
1 answer:
vekshin14 years ago
6 0
Mainly because of the higher energy of blue light than red light.

In fact, light is made of photons, each one carrying an energy equal to
E=hf
where h is the Planck constant while f is the frequency of the light.
The frequency of red light is approximately 450 THz, while the frequency of blue light is about 650 Hz. Higher frequency means higher energy, so blue light is more energetic than red light and therefore it can cause more damages than red light.
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Hannah is very good at picking up differences in other people's mood and behavior. She has been rewarded for her ability to work
Elanso [62]
It's C. Most likely
5 0
4 years ago
Read 2 more answers
In an eslastic ,the momentum is_______and the mechanical energy is​
DIA [1.3K]

Answer:

In an elastic collision, the momentum is conserved and the mechanical energy is conserved too.

Explanation:

There are two types of collisions:

- Elastic collision: in an elastic collision, the total momentum before and after the collision is conserved; also, the total mechanical energy before and after the collision is conserved.

- Inelastic collision: in an inelastic collision, the total momentum before and after the colllision is conserved, while the total mechanical energy is not conserved (in fact, part of the energy is converted into other forms of energy such that thermal energy, due to the presence of frictional forces)

3 0
3 years ago
Show that the speed with which a projectile leaves the ground is equal to its speed just before it strikes the ground at the end
Rina8888 [55]

Answer:

Thus, the velocity at the time of strike is same as the velocity at the time of projection.

Explanation:

Let a projectile is projected vertically upwards with a speed of u and reaches to the maximum height H.

At maximum height , the speed is zero and then the projective comes back on the ground.

Use the third equation of motion

v^2 = u^2 + 2 g h \\\\0 = u^2 - 2 g H\\\\\u =\sqrt{2gH}

Now let the velocity at the time of strike is v'.

Use third equation of motion, here initial velocity is zero.  

v'^2 = 0 + 2 g H \\\\v = \sqrt{2gH}

Thus, the velocity at the time of strike is same as the velocity at the time of projection.

8 0
3 years ago
If a boat and its riders have a mass of 1100 kg and the boat drifts in at 1.3 m/s how much work does Sam do to stop it
andriy [413]

Answer:

-929.5Joules

Explanation:

To get the work done by sam, we will calculate the kinetic energy of sam expressed as;

KE = 1/2mv²

m is the mass = 1100kg

v is the velocity = 1.3m/s

KE = 1/2(1100)(1.3)²

KE = 550(1.69)

KE = 929.5Joules

Since Sam is opposing the direction of movement, work done by him will be a negative work i.e -929.5Joules

5 0
3 years ago
How to remember physics derivation easier? <br>​
polet [3.4K]

Answer:

hmm let's see

Explanation:

ok, ill use the second equation of motion, u see its quite simple

recall that

average velocity= u+v/2

now think of that v like a box you can can call it velocity lol obviously its velocity

now remember the first equation of motion which is

v=u+at now this is inside the box, now you have to replace the v with it

then it becomes u+u+at/2

now u notice there are two initial velocity u know what to do with that

now it becomes

2u + at/2 now since the numerator applies to both then you can simplify it like this

2u/2+at/2

all the same the pont im trying to make is that you can use imaginative ways to mater derivation you can also reverse it if you don't unferstand you can drop your number

7 0
3 years ago
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