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3 years ago

What physics principle is used in radar guns to find the speeds of tennis balls and baseballs at sporting events?

Physics

1 answer:

Luda [366]3 years ago

6 0

<h2>Answer: Doppler effect </h2>

Explanation:

A radar gun (also known as a Doppler radar) uses the Doppler effect when measuring "return echoes" after having sent a microwave signal (a type of electromagnetic radiation).

In this context the Doppler effect consists of the change in a wave perceived frequency when the emitter of the waves, and the observer move relative to each other.

In the case of radars, a microwave signal is sent to a target (the tennis or baseball in this case) and then is reflected after "hitting" the target, so that the radar system measures this difference between the sent signal and the reflected signal.

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A large fraction of the ultraviolet (UV) radiation coming from the sun is absorbed by the atmosphere. The main UV absorber in ou

irakobra [83]

Answer:

λ = 3.2 x 10⁻⁷ m = 320 nm

Explanation:

The relationship between the velocity of electromagnetic waves (UV rays) and the their frequency is:

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So, the radiation of <u>320 nm</u> wavelength is absorbed by Ozone.

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3 years ago

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A state patrol officer saw a car start from rest at a highway on-ramp. She radioed ahead to another officer 20 mi along the hig

Vikentia [17]

Answer:

We know from the basic speed distance relation that

$Speed=\frac{Distance}{Time}$

Since the car started from rest and it covered the distance between the 2 officer's in 19 minutes we have speed of the car

$Speed=\frac{Distance}{Time}\\\\Speed=\frac{20}{\frac{19}{60}}=63.16mph$

Which clearly exceeds the limit of $60\frac{mi}{hr}$

5 0

3 years ago

At a particular instant, a proton at the origin has velocity < 5e4, -2e4, 0> m/s. You need to calculate the magnetic field

vesna_86 [32]

Answer:

$9.7\times 10^{-5} T$

Explanation:

Velocity = $5\times 10^4i-2\times 10^4j$

r= $0.03i+0.05j$

r= $\mid r\mid=\sqrt{(0.03)^2+(0.05)^2}=0.058$

v= $\mid V\mid=\sqrt{(5\times 10^4)^2+(-2\times 10^{4})^2}=5.39\times 10^{2}$

We know that

$B=\frac{mv}{qr}$

Where q= $1.6\times 10^{-19} C$

Mass of proton= $1.67\times 10^{-27} kg$

Using the formula

$B=\frac{1.67\times 10^{-27}\times 5.39\times 10^2}{1.6\times 10^{-19}\times 0.058}$

$B=9.7\times 10^{-5} T$

3 0

3 years ago

Bicyclists in the Tour de France do enormous amounts of work during a race. For example, the average power per kilogram generate

tigry1 [53]

Explanation:

It is given that,

Average power per unit mass generated by Lance, $\dfrac{P}{m}=6.5\ W/kg$

$P=6.5\times 75=487.5\ W$

(a) Distance to cover race, $d = 160\ km =160\times 10^3\ m$

Average speed of the person, v = 11 m/s

If t is the time taken to cover the race.

$t=\dfrac{d}{v}$

$t=\dfrac{160\times 10^3\ m}{11\ m/s}$

t = 14545.46 s

Let W is the work done. The relation between the work done and the power is given by :

$P=\dfrac{W}{t}$

$W=P\times t$

$W=487.5\times 14545.46$

W = 7090911.75 J

(b) Since, $1\ J=2.389\times 10^{-4}\ calories$

So, in 7090911.75 J, $W=7090911.75 \times 2.389\times 10^{-4}$

W = 1694.01 J

Hence, this is the required solution.

6 0

3 years ago