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Maslowich
3 years ago
14

When the distance between a point source of light and a light meter is reduced from 6.0m to 2.0 m, the intensity of illumination

at the meter will be the original value multiplied by _____.
Physics
1 answer:
Sergeeva-Olga [200]3 years ago
7 0

Answer:

Explanation:

Let the point source have power P .

At distance r , the intensity I

I = P / 4πr² . If intensity at 6 m and 2 m be I₁ and I₂

I₁ = P / 4π x 6²

I₂ =  P / 4π x 2²

I₁ / I₂ = 2² / 6²

= 1 / 9

I₂ = 9 I₁

Intensity will be 9 times that at 6 m .

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A circular wooden loop of mass m and radius R rest on a flat horizontal friction less surface. A bullet, also of mass m, and mov
bearhunter [10]

Answer:

w = vR/3

Explanation:

The centre of mass of the loop to bullet system is given by D / 4 from centre of loop, which is equivalent to R / 2 from its centre.

From the principle of conservation of linear momentum , we have

m*v = 2*m* Vcm

Where v = velocity of bullet, Vcm = velocity of wood

Hence, we have  

Vcm = v2

Also, from the conservation of angular momentum about the centre of mass.

M*V*(R/2) = Ic*w - equation (I)

where Ic = moment of inertia and w = angular velocity

Ic for a ring is given by mr^2 + m(r/2)^2

Ic of a bullet is given by m(r/2)^2

Hence, the moment of inertia of the system  is given by the summation of the two moments of inertia Ic(ring) + Ic(bullet) which gives

Ic(system) = 3*m*R^2/2

Substituting back into equation (I), we have

m*v*R^2=3*m*R^2*w/2

Hence, we obtain w =vR/3

w=v3R

4 0
3 years ago
Does a compressed spring transfer elastic energy to its surroundings?
shusha [124]

Answer:

Yes

Explanation:

5 0
3 years ago
Which subatomic particle has the least mass?
goblinko [34]

Answer:

electron

Explanation:

6 0
3 years ago
A rock, initially at rest with respect to Earth and located an infinite distance away is released and accelerates toward Earth.
lianna [129]

Answer:

the rock speed is increased

7 0
3 years ago
Tina is driving her sports car down US1, traveling 27m/s. She sees her friend Rita up ahead, waiting to cross the street at the
mrs_skeptik [129]

Answer:

434 Hz

Explanation:

According to the Doppler effect, when a source of a wave is moving towards an observer at rest, then the observer will observe an apparent frequency which is higher than the original frequency of the source.

In this situation, Tina is driving towards Rita. Tina is the source of the sound wave (the horn), while RIta is the observer. Since the original frequency of the sound is 400 Hz, Rita will hear a sound with a frequency higher than this value.

The only choice which is higher than 400 Hz is 434 Hz, so this is the frequency that Rita will hear.

3 0
2 years ago
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