3 years ago

What does the blackboard do when white light falls on it?

1 answer:

5 0

Actually a black board has all colours in light or white light . So when light falls on it board absorbs all colours because all are present so no light is reflected back. That is the case, and so it will appear black as it absorbs all colours of light that fall on it .

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In which medium does sound travel faster

9966 [12]

It travels fastest through solids.

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3 years ago

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An RC circuit takes t = 2.5 ms to charge to 35% of its full charge after it weas connected to a battery, What is the total time

marin [14]

Answer: time taken to charge to 95%

t = -5.80[ln(1-0.95)]

t = 17.38ms

Explanation:

For an RC Charging circuit

Where Vs

Vc = Vs (1 - e^(-t/RC))

Vc/Vs = 1 - e^(-t/RC)

-t/RC = ln(1 - Vc/Vs)

t = -RC[ln(1 - Vc/Vs)] and RC = k = -t/ln(1 - Vc/Vs)

Where ;

Vc = voltage across the capacitor

Vs = voltage supply

t = charging time = 2.5ms

k = RC = time constant.

Vc/Vs = 0.35

To calculate the time constant k;

k = -t/ln(1- Vc/Vs)

k = -2.5/ln(1-0.35)

k = 5.80ms

time taken to charge to 95%

t = -5.80[ln(1-0.95)]

t = 17.38ms

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3 years ago

Is soy sauce a heterogeneous or homogeneous mixture?

harkovskaia [24]

Soy sauce is a homogeneous mixture.

3 0

3 years ago

A massless spring with force constant ????=200N/m hangs from the ceiling. A 2.0-kg block is attached to the free end of the spri

Makovka662 [10]

Answer:

-0.4454 Joules

Explanation:

m = Mass of block = 2 kg

h = Height of extension = 17 cm = x

g = Acceleration due to gravity = 9.81 m/s²

Potential energy of the spring

$P=mgh\\\Rightarrow P=2\times 9.81\times 0.17\\\Rightarrow P=3.3354\ J$

The kinetic energy of the spring

$K=\frac{1}{2}mx^2\\\Rightarrow K=\frac{1}{2}\times 200\times 0.17^2\\\Rightarrow K=2.89\ J$

In this system as the potential and kinetic energy is conserved from work energy equivalence we get

$W=P-K\\\Rightarrow W=2.89-3.3354\\\Rightarrow W=-0.4454\ J$

The work done by friction is -0.4454 Joules

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3 years ago

Suppose a net force of 7900 N is applied to slide a 950 kg crate across the floor. Compute the resulting acceleration of the cra

LiRa [457]

Explanation:

F=ma

7900=950a

a=7900/950=8.58m/s^2

4 0

3 years ago

What does the blackboard do when white light falls on it?​

What does the blackboard do when white light falls on it?