Please, I need help!

snow_lady [41]

politics. Famous possible eg is of Werner Heisenberg in WW2. He delayed German attempt to build a nuclear bomb. US did build one ... hiroshima and nagasaki.

debbie may have got skilfully lucky by trial and error

6 0

3 years ago

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A car travels from point A to point B, moving in the same direction but with a non-constant speed. The first half of the distanc

Dmitrij [34]

Answer:

Explanation:

From A to B

distance traveled with velocity $v_1$ in time $t_1$

$\frac{d}{2}=v_1t_1----1$

from B to C

distance traveled is 0.5 d with $v_2$ and $v_3$ velocity for half-half time

$\frac{d}{2}=\frac{v_2t_2}{2}+\frac{v_3t_3}{2}----2$

divide 1 and 2 we get

$\frac{1}{1}=\frac{2v_1t_1}{v_2t_2+v_3t_3}$

$\frac{t_1}{t_2}=\frac{v_2+v_3}{2v_1}$

Now average velocity is given by

$v_{avg}=\frac{d}{t_1+t_2}$

taking $t_1$ common

$v_{avg}=\frac{2v_1t_1}{t_1(1+\frac{t_2}{t_1})}$

$v_{avg}=\frac{2v_1}{1+\frac{2v_1}{v_2+v_3}}$

$v_{avg}=\frac{2v_1(v_2+v_3)}{2v_1+v_2+v_3}$

6 0

4 years ago

A fisherman notices that his boat is moving up and down periodically, owing to waves on the surface of the water. It takes 3.50

kkurt [141]

Answer:

a) speed= 0.86m/s

b) Amplitude = 0.35m

C) Amplitude = 0.25m

Explanation: correct values in question (for the boat to travel from its highest point to its lowest, a total distance of 0.700 m . The fisherman sees that the wave crests are spaced 6.00 m apart.)

The speed of a periodic wave with wavelength and frequency is given by:

Speed = frequency × wavelength

The relation between the time period and frequency is given by:

T = 1/f

Given:

Time that the boat takes to travel from the highest point to its lowest point,t = 3.50s

Distance between the lowest point and the highest point,d = 0.70m

Wavelength = 6.0m

a) Wavelength is the distance between two successive wave crests or troughs. So, the distance between the Crest (highest point) to the next(lowest point) is a half wavelength.

The time period ,T is the time between two successive waves.

Therefore,the time it takes the boat to travel from its highest point to its lowest point is period.

T = 2 ×3.50 =7.0seconds

Frequency, f = 1/7.0

f = 0.1429Hz

Speed = frequency × wavelength

Speed = 0.1429 × 6 = 0.86m/s

b) The amplitude is the maximum magnitude of displacement from equilibrium.

Therefore, the distance between the boar's highest point to its lowest point is

Amplitude, A = distance /2

Amplitude A = 0.70/2= 0.35m

c) If the vertical distance changes to d2= 0.50m but other data remained the same, this wont change the speed of the wave because it does not depend on the vertical displacement but it will change the amplitude

A = distance /2 = 0.50m/2 = 0.25m

7 0

3 years ago

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Electromagnetic waves carry energy. This phenomenon is also called electromagnetic radiation. How is energy transferred in elect

Anastasy [175]

Answer:

Energy is carried by the electric and magnetic fields

Explanation:

Electromagnetic waves consist of electric fields and magnetic fields which oscillate perpendicularly to the direction of propagation of the waves (for this reason, they are called transverse waves).

Electric fields and magnetic fields both possess energy, and this energy is carried through space by the wave. Note that electromagnetic waves do not carry matter, but only energy (in fact, they do not have mass). Moreover, electromagnetic waves are the only type of waves that do not need a medium to propagate: in fact, they can also travel through a vacuum.

6 0

3 years ago

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Rest and motion are relatives terms justify the statement

Anna007 [38]

Answer:

rest and motion are the relative terms because they depend on the observer's frame of reference. So if two different observers are not at rest with respect to each other, then they too get different results when they observe the motion or rest of a body

Explanation:

3 0

3 years ago