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jek_recluse [69]
3 years ago
12

A stationary speed gun emits a microwave beam at 2.10*10^10Hz. It reflects off a car and returns 1030 Hz higher. What is the spe

ed of the car?
Physics
1 answer:
KIM [24]3 years ago
8 0

Answer: V = 15 m/s

Explanation:

As  stationary speed gun emits a microwave beam at 2.10*10^10Hz. It reflects off a car and returns 1030 Hz higher. The observed frequency the car will be experiencing will be addition of the two frequency. That is,

F = 2.1 × 10^10 + 1030 = 2.100000103×10^10Hz

Using doppler effect formula

F = C/ ( C - V) × f

Where

F = observed frequency

f = source frequency

C = speed of light = 3×10^8

V = speed of the car

Substitute all the parameters into the formula

2.100000103×10^10 = 3×10^8/(3×10^8 -V) × 2.1×10^10

2.100000103×10^10/2.1×10^10 = 3×108/(3×10^8 - V)

1.000000049 = 3×10^8/(3×10^8 - V)

Cross multiply

300000014.7 - 1.000000049V = 3×10^8

Collect the like terms

1.000000049V = 14.71429

Make V the subject of formula

V = 14.71429/1.000000049

V = 14.7 m/s

The speed of the car is 15 m/s approximately.

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Photovoltaic cells are the most efficient means of converting solar energy to electricity. Option b is correct.

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Photovoltaic cells are the most efficient means of converting solar energy to electricity.

Hence, option b is correct.

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2 years ago
Examine the layers of rock. Identify and explain which layer contains the youngest fossils.
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3 years ago
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A mass of 10.0 kg is in a gravitational field of 3.50 N/kg. What force acts on the mass?
mash [69]

Answer:

Force=35 N

Explanation:

Given data

mass m=10.0 kg

Gravitational field E=3.50 N/kg

To find

Force

Solution

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Does Drag Oppose Lift​
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8 0
3 years ago
two electrons are an angstrom (1x10^-10m) apart. What electrostatic force do they exert on one another?
Irina-Kira [14]

Answer:

2.30 × 10⁻⁸ N if the two electrons are in a vacuum.

Explanation:

The Coulomb's Law gives the size of the electrostatic force F between two charged objects:

\displaystyle F = -\frac{k\cdot q_1 \cdot q_2}{r^{2}},

where

  • k is coulomb's constant. k = 8.99\times 10^{8}\;\text{N}\cdot\text{m}^{2}\cdot\text{C}^{-2} in vacuum.
  • q_1 and q_2 are the signed charge of the objects.
  • r is the distance between the two objects.

For the two electrons:

  • q_1 = q_2 = 1.60\times 10^{-19}\;\text{C}.
  • r = 1\times 10^{-10}\;\text{m}.
  • \displaystyle F = -\frac{k\cdot q_1 \cdot q_2}{r^{2}} = -\frac{8.99\times 10^{8}\times (1.60\times 10^{-19})^{2}}{(1\times 10^{-10})^{2}} = 2.30\times 10^{-8}\;\text{N}.

The sign of F is negative. In other words, the two electrons repel each other since the signs of their charges are the same.

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