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Can someone plz explain this question...
View attachment 62738
A is incorrect because microwaves have more energy than radio waves. This means that the microwaves have a higher frequency and therefore lower wavelength.and
Microwaves are used to transmit television signals to and from a satellite.
Which statement about microwaves is correct?
A They have a longer wavelength than radio waves.
B They penetrate the atmosphere without significant loss of energy.
C They travel much faster than radio waves in a vacuum.
D They warm the satellite and stop it freezing.
why is it B
Thought I'd just make D a little clearer: the main problem is the sun overheating the satellite, rather than freezing, ironically.A is incorrect because microwaves have more energy than radio waves. This means that the microwaves have a higher frequency and therefore lower wavelength.
C is incorrect as all electromagnetic waves travel at the same speed in space i.e. 3x10^8 ms^-1.
And D is just absolutely ridiculous.
By way of elimination, B is the answer which makes the most sense.
By Kirchhoff's law of the conservation of charge, the current in wire R must be 2A into the junction, as current in=current out.How to do this??
-------------------------
The diagram shows a junction in a circuit where three wires
P, Q and R meet. The currents in P and Q are 1 A and 3 A
respectively, in the directions shown.
How many coulombs of charge pass a given point in wire R in
5s?
A) 0.4 B) 0.8 C) 2 D) 10
Figure out the vertical component of the velocity first. The vertical component of the velocity is 50sin23. Now you know the rate at which the height of the plane increases.A loaded aeroplane has a total mass of 1.2x10^5 kg while climbing after take off. It climbs at an agle 23 degree to horizontal with a speed of 50 m/s. what is the rate at which it is gaining potential energy at this time?
ans: 2.3x10^7
First use Q=It to obtain the current through the circuit.34. C
Suppose the diameter of the wider portion is 2r, so its radius will be r and area will be pi x r²View attachment 62752
this might be a very easy question,but i dont seem to get it.
the answer is A.
please helppp!
STRESS= FORCE/AREAView attachment 62752
this might be a very easy question,but i dont seem to get it.
the answer is A.
please helppp!
STRESS= FORCE/AREA
Stress (wide) =F/[d^2]
Stress (narrow)= F/[(d/2)^2]
F and d^2 will cancel out each other by substituting them.
StressW/StressN= [1]/[4]
=0.25
Suppose the diameter of the wider portion is 2r, so its radius will be r and area will be pi x r²
Since the dia of the narrow portion is half, so it will be r and its radius will be r/2=0.5r and area will be pi x (0.5r)²= pi x 0.25r²
Now the ratio of stress will be (T/pi x r²) / (T/ pi x 0.25 r²)
T and pi will be cancelled out and This will be simplified to (1/r²)/(1/0.25r²)= 0.25
Hope it helps
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