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3 years ago

Why can concave mirror is used in cosmetic mirror

1 answer:

5 0

A concave mirror is a curved mirror that bulges inward. Objects reflected in concave mirrors often appear bigger than they really are, although the specifics of how the image appears depends upon the object's distance from the mirror. Concave mirrors are used in car headlights, in dentist's offices and in makeup mirrors.

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Write two examples of machine which increases the speed of doing work

julia-pushkina [17]

Answer:

Explanation:

Speed multipliers are useful when an object needs to move a further distance or at a higher speed. Some examples are wheels and axles and third class levers. Machines can be either simple or complex. Simple machines are machines that only use one type of machine, such as a lever or an inclined plane.

6 0

3 years ago

Read 2 more answers

Volume of a cylinder with a diameter of 1.55 cm and a height of 1.34 cm

Bogdan [553]

Answer:

2.53 cm³

Explanation:

Volume of cylinder = πr²h; where h is the height and r is the radius and

π = 3.14 approx.

Volume = 3.14 * (1.55/2)² * 1.34 = 2.53 cm³

I divided 1.55 by 2 because we were given the diameter and not radius. Diameter = radius / 2

4 0

3 years ago

A resistor with an unknown resistance is connected in parallel to a 13 Ω resistor. When both resistors are connected in parallel

larisa86 [58]

Answer:

R2 = 10.31Ω

Explanation:

For two resistors in parallel you have that the equivalent resistance is:

$\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2}\\\\$ (1)

R1 = 13 Ω

R2 = ?

The equivalent resistance of the circuit can also be calculated by using the Ohm's law:

$I=\frac{V}{R_{eq}}\\\\R_{eq}=\frac{V}{I}$ (2)

V: emf source voltage = 23 V

I: current = 4 A

You calculate the Req by using the equation (2):

$R_{eq}=\frac{23V}{4A}=5.75\Omega$

Now, you can calculate the unknown resistor R2 by using the equation (1):

$\frac{1}{R_2}=\frac{1}{R_{eq}}-\frac{1}{R_1}\\\\R_2=\frac{R_{eq}R_1}{R_1-R_{eq}}\\\\R_2=\frac{(5.75\Omega)(13\Omega)}{13\Omega-5.75\Omega}=10.31\Omega$

hence, the resistance of the unknown resistor is 10.31Ω

8 0

3 years ago

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Hardness is indirectly related to: specific gravity surface roughness strength of chemical bonds weight

Zepler [3.9K]

The strength of chemical bonds would be the best answer to this question. Hardness is indirectly related to the strength of chemical bonds. Hardness is the resistance from the destruction of an object itself from a material. Hardness does not need to strength of chemical bonds in order to have this resistance.

5 0

3 years ago

Read 2 more answers

calculate the critical angle of water if the velocity of light in water is 2.2×10^8m/s. ( given, velocity of light in air = 3× 1

artcher [175]

Speed of light in vacuum = 3.0 × 10⁸ m/s

Speed of light in water = 2.25 x 10⁸ m/s

Refractive index of water = ?

We know that

Refractive index of water = $\frac{Speedoflightinvacuum}{speedoflightinwater}$