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3 years ago

If you see a lightning stroke and then, 15 seconds later, hear the thunder, the lightning is about ____ miles away

Physics

1 answer:

makvit [3.9K]3 years ago

3 0

Answer:

3.2 miles

Explanation:

We can assume that the light coming from the lightning reach instantaneously our eyes (because light travels very fast, $3\cdot 10^8 m/s$ ), so the time between the lightining and the hearing of the thunder is equal to the time that sound takes to each us.

Sound travels in air approximately at speed

v = 343 m/s

So the distance it covers in a time of t = 15 seconds is

$d=vt=(3403 m/s)(15 s)=5145 m$

And using the conversion from meters to miles,

1 mile = 1609 meters

we find

$d=\frac{5145 m}{1609 m/miles} = 3.2 miles$

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Two cars travel in the same direction along a straight highway, one at a constant speed of 55 mi/h and the other at 60 mi/h.How

Pachacha [2.7K]

Answer:

The distance traveled by the faster car when it is 15 mins ahead of the slower car is 165 miles.

Explanation:

Given;

speed of the faster car, v₁ = 60 mi/h

speed of the slower car, v₂ = 55 mi/h

Let the distance traveled by the faster car when it is 15 mins ahead of the slower car = x miles

$\frac{x}{55} - \frac{x}{60} = \frac{15}{60}$

Note: divide 15 mins by 60 to convert to hours for consistency in the units.

$\frac{x}{55} - \frac{x}{60} = \frac{15}{60}\\\\multiple \ through \ by \ 660\\\\12x - 11x = 165\\\\x = 165 \ miles$

Therefore, the distance traveled by the faster car when it is 15 mins ahead of the slower car is 165 miles.

4 0

2 years ago

A 230-km-long high-voltage transmission line 2.0 cm in diameter carries a steady current of 1,100 A. If the conductor is copper

Molodets [167]

Answer:

28.23 years

Explanation:

I = 1100 A

L = 230 km = 230, 000 m

diameter = 2 cm

radius, r = 1 cm = 0.01 m

Area, A = 3.14 x 0.01 x 0.01 = 3.14 x 10^-4 m^2

n = 8.5 x 10^28 per cubic metre

Use the relation

I = n e A vd

vd = I / n e A

vd = 1100 / (8.5 x 10^28 x 1.6 x 10^-19 x 3.14 x 10^-4)

vd = 2.58 x 10^-4 m/s

Let time taken is t.

Distance = velocity x time

t = distance / velocity = L / vd

t = 230000 / (2.58 x 10^-4) = 8.91 x 10^8 second

t = 28.23 years

5 0

3 years ago

Read 2 more answers

In Europe, gasoline efficiency is measured in km/L. If your car's gas mileage is 36.0mi/gal , how many liters of gasoline would

Zigmanuir [339]

$36 \frac{mi}{gal} * \frac{1 km}{0.6214 mi}* \frac{1 gal}{3.78 L} = 15.3 \frac{km}{L}

142/15.3=9.27L$

3 0

2 years ago

A hot air balloon is traveling vertically upward at a constant speed of 4.5 m/s. When it is 28 m above the ground, a package is

ella [17]

Answer:

1.97 seconds

Explanation:

t = Time taken

u = Initial velocity

v = Final velocity

s = Displacement

a = Acceleration due to gravity = 9.8 m/s²

$s=ut+\frac{1}{2}at^2\\\Rightarrow 21=4.5t+\frac{1}{2}\times -9.8\times t^2\\\Rightarrow 21=-4.5t-4.9t^2\\\Rightarrow 4.9t^2+4.5t-28=0\\\Rightarrow 49t^2+45t-280=0$

Solving the above equation we get

$t=\frac{-45+\sqrt{45^2-4\cdot \:49\left(-280\right)}}{2\cdot \:49}, \frac{-45-\sqrt{45^2-4\cdot \:49\left(-280\right)}}{2\cdot \:49}\\\Rightarrow t=1.97, -2.89$

So, the time the package was in the air is 1.97 seconds

3 0

2 years ago

A parallel plate air capacitor has a capacitance of 10 to the power -9. What potential difference is required for a charge of 5×

Maurinko [17]

The potential difference across the capacitor is 5 × 10∧4 volts and the energy stored in it is 1. 25 Joules

<h3>What is the energy in a capacitor?</h3>

The energy stored in a capacitor is an electrostatic potential energy.

It is related to the charge(Q) and voltage (V) between the capacitor plates.

It is represented as 'U'.

<h3>How to determine the potential difference</h3>

Formula:

Potential difference, V is the ratio of the charge to the capacitance of a capacitor.

It is calculated using:

V = Q ÷ C

Where Q = charge 5 × 10∧-5C and C = capacitance 10∧-9

Substitute the values into the equation

Potential difference, V = 5 × 10∧-5 ÷ 10∧-9 = 5 × 10∧4 volts

<h3>How to determine the energy stored</h3>

Formula:

Energy, U = 1 ÷ 2 (QV)

Where Q= charge and V = potential difference across the capacitor

Energy, U = 1 ÷ 2 ( 5 × 10∧-5 × 5 × 10∧4)

= 0.5 × 25 × 10∧-1

= 0.5 × 2.5

= 1. 25 Joules

Therefore, the potential difference across the capacitor is 5 × 10∧4 volts and the energy stored in it is 1. 25 Joules

Learn more about capacitance here:

brainly.com/question/14883923

#SPJ1

6 0

1 year ago