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3 years ago

11

Plzzz Help

1 answer:

m_a_m_a [10]3 years ago

8 0

Answer:

The electromagnetic waves appear more blue in color.

Explanation:

Doppler's Effect: When a source moves with respect to the observer the frequency of the wave emitted from the source changes. If the source moves away from the observer, the frequency decreases and wavelength increases and vice versa.

Here the light source is moving towards the observer so the frequency will increase and wavelength will decrease. Thus the spectrum will shift towards the blue part. This is known as blue shift. The light wave will appear blue in color.

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When an 8 V battery is connected to a resistor, a 2 A current flows in the resistor. What is the resistor's value?

Vinvika [58]

Answer:

B

Explanation:

V=IR I= curren V=volt R=resistor

8=2.R 8/2=R R=4

5 0

3 years ago

As you stand by the side of the road, a car approaches you at a constant speed, sounding its horn, and you hear a frequency of 8

kap26 [50]

Answer: velocity of the car is 113.33m/s

Explanation:

From Doppler effect,

in the case which the source is moving towards the observer at rest

f2 = v/(v-vs) *f1

where f2 is the final observed frequency

f1 is the initial observed frequency

v = 340m/s (speed of sound in air)

vs = velocity of the source of sound.

rearranging the above equation

f2*(v - vs) = f1* v

vs = (f1* v/f2) - v

but f1 = 80Hz

f2 = 60Hz

v = 340m/s

substituting,

vs = (80 x 340)/60 - 340

vs = 453.33 - 340

vs = 113.33m/s

velocity of the car is 113.33m/s

5 0

3 years ago

An open system starts with 52 J of mechanical energy. The energy changes

spayn [35]

Answer:

I think the answer is D,54 joules

5 0

2 years ago

(a) At what height above Earth’s surface is the energy required to lift a satellite to that height equal to the kinetic energy r

Nikitich [7]

Answer:

Explanation:

Gravitational Potential Energy at earth surface $U_1=\frac{GM_em}{R_e}$

Gravitational Potential Energy at height h is $U_2=\frac{GM_em}{R_e+h}$

Energy required to lift the satellite $E_1=U_1-U_2$

$E_1=\frac{GM_em}{R_e}-\frac{GM_em}{R_e+h}$

Now Energy required to orbit around the earth

$E_2=\frac{1}{2}mv_{orbit}^2=\frac{GM_2m}{2(R_e+h)}$

$\Delta E=E_1-E_2$

$\Delta E=\frac{GM_em}{R_e}-\frac{GM_em}{R_e+h}-\frac{GM_2m}{2(R_e+h)}$

$E_1=E_2$ (given)

$\frac{GM_em}{R_e}-\frac{GM_em}{R_e+h}-\frac{GM_2m}{2(R_e+h)}=0$

$\frac{1}{R_e}-\frac{3}{2(R_e+h)}=0$

$h=\frac{R_e}{2}$

$h=3.19\times 10^6\ m$

(b)For greater height $E_1$ is greater than $E_2$

thus energy to lift the satellite is more than orbiting around earth

4 0

3 years ago

A 25 kg child is riding on a swing. If the child travels 8.9 m/s at the bottom of their swing, how high into the air is the chil

Setler [38]

Answer:

h = 4.04 m

Explanation:

Given that,

Mass of a child, m = 25 kg

The speed of the child at the bottom of the swing is 8.9 m/s

We need to find the height in the air is the child is able to swing. Let the height is h. Using the conservation of energy such that,

$mgh=\dfrac{1}{2}mv^2\\\\h=\dfrac{v^2}{2g}$

Put all the values,

$h=\dfrac{(8.9)^2}{2\times 9.8}\\\\h=4.04\ m$

So, the child is able to go at a height of 4.04 m.

7 0

3 years ago