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gavmur [86]
2 years ago
7

Help with the two questions above? Correct answers?

Physics
1 answer:
LenKa [72]2 years ago
7 0

(6) first choice: the frequency appears higher and wavelength is shorter.

The car approaches a stationary observer and so the sound will appear to have shorter wavelength. This creates an effect of its siren to sound with higher frequency than it would do if both were stationary.

(7) The Doppler formula for frequency in the case of a stationary observer and source approaching it is as follows:

f_O = \frac{v}{v-v_s}\cdot f= \frac{343\frac{m}{s}}{(343-25)\frac{m}{s}}\cdot 400Hz \approx 431Hz

The wavelength is then

\lambda = \frac{343\frac{m}{s}}{431Hz}\approx 0.80 m

The third choice "0.80m; 431Hz" is correct

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A proton and an electron are moving in the +x direction in a magnetic field in the +z
Aleksandr [31]

Answer:

Explanation:

Force on a moving charge is given by the following relation

F = q ( v x B )

for proton

q = e  ,   v = vi  , B = Bk

F = e ( vi x Bk )

= Bev - j

= - Bevj

The direction of force is along negative of y axis or -y - axis.

for electron

q = - e  ,   v = vi  , B = Bk

F = - e ( vi x Bk )

= - Bev - j

=  Bevj

The direction of force is along positive  of y axis or + y - axis.

5 0
3 years ago
Which relations below regarding magnetic field and electric field lines are true? 1. Magnetic field lines never begin nor end bu
Vlad1618 [11]

Answer:

Options 1 and 5 are correct

Explanation:

Magnetic field lines can never cross, the field is unique at any point in space. Magnetic field lines are continuous, forming closed loops without beginning or end. They go from the north pole to the south pole.

Magnetic field lines form closed loops but do not intersect.

Electric field lines originate at the positive charges and terminate at the negative charges. They move in a straight line and are parallel. Electric field lines neither form closed loops nor intersect.

Since, magnetic field lines form closed loops and move from North to South pole, they come out of north poles outside the magnet and into north poles inside the magnet, they also go into south poles outside the magnet and out of south poles inside the magnet.

3 0
3 years ago
Correct shape will reduce fluid friction.<br> True <br> False
AURORKA [14]
I believe that is true.

hope this helps!
8 0
3 years ago
Read 2 more answers
Alan and Monica tested how fertilizer X affected the growth of a plant. Alan and Monica put 100 grams of fertilizer X in pot 1.
BARSIC [14]

Answer:

D.

a control group

Explanation:

In a scientific experiment such as the one above, there is an experimental group and a control group. The experimental group is the group that receives the treatment while the control group does not receive any treatment. The control group helps the researcher to observe if the treatment had any significant effect.

In this case, it will help Alan and Monica to determine if fertilizer X actually had an effect on the plant. Therefore, the pot with o grams of fertilizer in it is the control group.

7 0
2 years ago
A 0.40-kg mass attached to the end of a string swings in a vertical circle having a radius of 1.8 m. At an instant when the stri
san4es73 [151]

Answer:

T = 8.55 N

Explanation:

When string makes an angle 40 degree with the vertical then it will have two forces on it

1) gravitational force (mg)

2) Tension force in string (T)

now we know that net force towards the center of the path is known as centripetal force and it is given as

T - mg cos40 = F_c

T - (0.40\times 9.8)cos40 = \frac{mv^2}{L}

T = 3 + \frac{0.40\times 5^2}{1.8}

T = 3 + 5.55

T = 8.55 N

6 0
2 years ago
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