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3 years ago

12

A boy walks towards a stationary plane mirror at a speed of 12ms^1 what is the relative speed of approach of the boy and his ima

ge? (a)zero (b)1.2ms^-1 (c) 2.4ms^-1 (d)1.44ms^-1

1 answer:

Vitek1552 [10]3 years ago

3 0

Answer:

a

Explanation:

mark me as brainlist ez

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Generation of electricity in coal-burning power plants and nuclear power plants both involve _______.

kolbaska11 [484]

Answer:

Heating water to produce steam which drives a turbine

Explanation:

Generation of electricity in coal-burning power plants and nuclear power plants both involve heating water to produce steam which drives a turbine.

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3 years ago

An ore car of mass 39000 kg starts from rest and rolls downhill on tracks from a mine. At the end of the tracks, 25 m lower vert

Musya8 [376]

Answer:

x = 5.79 m

Explanation:

given,

mass of the car = 39000 Kg

spring constant = 5.7 x 10⁵ N/m

acceleration due to gravity = 9.8 m/s²

height of the track = 25 m

length of spring compressed = ?

using conservation of energy

potential energy is converted into spring energy

$m g h = \dfrac{1}{2}kx^2$

$x =\sqrt{\dfrac{2 m g h}{k}}$

$x =\sqrt{\dfrac{2\times 39000 \times 9.8 \times 25}{5.7 \times 10^{5}}}$

$x =\sqrt{33.5263}$

x = 5.79 m

the spring is compressed to x = 5.79 m to stop the car.

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3 years ago

Elanso [62]

Answer:

Well, their are two answers in their. It would be Ask their Parent for assistance in persuading and Ask for an opportunity to earn extra credit:)

Explanation:

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3 years ago

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The radius of Earth is . The average Earth-Sun distance is . How many Earths would fit between Earth and the Sun if they are sep

Verdich [7]

Answer:

The radius of the earth is 6,371 km.

The average Earth-Sun distance is 152.09 million km

How many Earths would fit between Earth and the Sun if they are separated by their average distance? Approximately 11,936 Earths.

I didn't really understand the last part, but if you don't get a better answer please mark me as brainliest.

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3 years ago

Scientific work is currently underway to determine whether weak oscillating magnetic fields can affect human health. For example

ValentinkaMS [17]

Answer:

$2.02672\times 10^{-11}\ V$

Explanation:

f = Frequency = 75 Hz

B = Magnetic field = $1\times 10^{-3}\ T$

d = Diameter of cell = $7.4\ \mu m$

t = Time taken

$\omega$ = Angular frequency

The expression of emf is

$E=NAB\omega sin\omega t$

Emf is maximum when $sin\omega t=1$ and N = number of turns = 1

$E_m=AB\omega\\\Rightarrow E_m=\pi \left(\frac{d}{2}\right)^2 \times B \times 2\pi\times f\\\Rightarrow E_m=\pi \left(\frac{7.4\times 10^{-6}}{2}\right)^2\times 1\times 10^{-3}\times 2\pi\times 75\\\Rightarrow E_m=2.02672\times 10^{-11}\ V$

The maximum emf that can be generated around the perimeter of a cell in this field is $2.02672\times 10^{-11}\ V$

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3 years ago