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3 years ago

According to the inverse square law of light, if you double your distance to a source, the brightness will...

Physics

2 answers:

blondinia [14]3 years ago

7 0

Answer:

option (b)

Explanation:

According to the inverse square law,

$Brightness \alpha \frac{1}{distance^{2}}$

As the distance is doubles, the brightness becomes one fourth.

It means the brightness decreases by a factor of 4.

Option (b)

GalinKa [24]3 years ago

6 0

Answer:

a. decrease by a factor of 3.

Explanation:

The intensity of light is inversely proportional to the square of distance.

I ∝1/d^2

I= k/d^2

where k is a constant

so, if d becomes 2d , I will be come I/4

Therefore, intensity will a. decrease by a factor of 3.

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A figure skater begins spinning counterclock-

wlad13 [49]

Answer:

Angular acceleration, $\alpha =0.64\ rad/s^2$

Explanation:

Given that,

Initial angular velocity, $\omega_i=4.67\ rad/s$

The final angular velocity, $\omega_f=7.37\ rad/s$

Time, t = 4.2 s

We need to find her average angular acceleration during this time interval. Acceleration is the rate of change of velocity. So,

$\alpha =\dfrac{\omega_f-\omega_i}{t}\\\\\alpha =\dfrac{7.37-4.67}{4.2}\\\\\alpha =0.64\ rad/s^2$

So, her average angular acceleration is $0.64\ rad/s^2$ .

3 0

3 years ago

What is the surface area to volume ratio of this cube

Ipatiy [6.2K]

The edge of the cube is 5 cm.
The volume of the cube is (5cm) · (5 cm) · (5 cm) = (5 cm)³ = 125 cm³

The cube has 6 faces.
The area of each face is (5 cm) · (5 cm) = 25 cm²
The area of all 6 faces is (6) · (25 cm²) = 150 cm²

The ratio of its volume to its surface area is
the ratio of

(125 cm³) to (150 cm²)

= 5/6 cm⁻¹ .

3 0

4 years ago

Why is alpha rays not suitable to scan baggage at the airport?

Inga [223]

Answer:

Alpha particles are not used to check baggage in airport as these rays are not penetrated far through matter.

Explanation:

Alpha particles are produced by the decay of a radioactive nucleus. These alpha rays are ceased by paper. The nucleus of the helium atom is made up of two protons and two neutrons is the particle ejected by alpha particle.

As helium is harmless and as an inert gas, so these particles are not dangerous in themselves. The airport baggage security uses only X-ray scanners to inspect. These rays identify the hidden items inside the baggage.

4 0

3 years ago

A stone is thrown straight up from the ground with an initial speed of 44 m/s.At the same instant, a stone is dropped from a hei

Lubov Fominskaja [6]

Answer:

394.26 m

Explanation:

t = Time taken

u = Initial velocity

v = Final velocity

s = Displacement

a = Acceleration due to gravity = 9.8 m/s²

$v=u+at\\\Rightarrow 0=44-9.8\times t\\\Rightarrow \frac{-44}{-9.8}=t\\\Rightarrow t=4.49 \s$

$s=ut+\frac{1}{2}at^2\\\Rightarrow s=44\times 4.49+\frac{1}{2}\times -9.8\times 4.49^2\\\Rightarrow s=98.77\ m$

$s=ut+\frac{1}{2}at^2\\\Rightarrow 98.77=0t+\frac{1}{2}\times 9.8\times t^2\\\Rightarrow t=\sqrt{\frac{98.77\times 2}{9.8}}\\\Rightarrow t=4.49\ s$

Total time taken by the stone to reach the ground is 4.49+4.49 = 8.97 seconds

$s=ut+\frac{1}{2}at^2\\\Rightarrow h=0t+\frac{1}{2}\times 9.81\times t^2\\\Rightarrow t=\sqrt{\frac{h\times 2}{9.8}}$

The times are equal so,

$8.97=\sqrt{\frac{h\times 2}{9.8}}\\\Rightarrow h=\frac{8.97^2\times 9.8}{2}\\\Rightarrow h=394.26\ m$

The height is 394.26 m

6 0

3 years ago

Can someone help me with this please

rjkz [21]

Answer:

1. 2HCl + MgO —-> MgCl2 + H2O

Explanation: You add a 2 in front of the HCl in order to have 2 hydrogens on each side and 2 Cl on each side. Since, Magnesium only has one on each side, they’re already balanced. Same with Oxygen so you leave it alone.

4 0

3 years ago