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3 years ago

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You have been called to testify as an expert witness in a trial involving a head-on collision. Car A weighs 1515 lb and was trav

eling eastward. Car B weighs 1125 lb and was traveling westward at 43.0 mph. The cars locked bumpers and slid eastward with their wheels locked for 17.5 ft before stopping. You have measured the coefficient of kinetic friction between the tires and the pavement to be 0.750. How fast (in miles per hour) was car A traveling just before the collision? (This problem uses English units because they would be used in a U.S. legal proceeding.)

1 answer:

serious [3.7K]3 years ago

6 0

what was the speed limit, and it was 40 mph

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A wire must be replaced in a circuit by a new wire of the same material but nine times longer. If the new wire's resistance is t

Blizzard [7]

Answer:

three times the original diameter

Explanation:

From the wire's resistance formula, we can calculate the relation between the diameter of the wire and its length:

$R=\rho\frac{l}{\pi \frac{d^2}{4}}\\d=\sqrt{\rho \frac{4 l}{\pi R}}\\$

Here, d is the wire's diameter, $\rho$ is the electrical resistivity of the material and R is the resistance of the wire. We have $l'=9l$

$d'=\sqrt{\rho \frac{4 l'}{\pi R}}\\d'=\sqrt{\rho \frac{4 (9l)}{\pi R}}\\d'=3\sqrt{\rho \frac{4 l}{\pi R}}\\d'=3d$

7 0

3 years ago

Draw a schematic diagram of a circuit consisting of a battery of five 2 V cells, a 5 ohm resistor, a 10 ohm resistor, a 15 ohm r

MakcuM [25]

Answer:

Current = 0.33 A

Explanation:

For diagram refer the attachment.

It is given that five cells of 2V are connected in series, so total voltage of the battery:

$\dashrightarrow \: \: \sf V = 2 \times 5 = 10 V$

Three resistor of 5 $\Omega$ , 10 $\Omega$ , 15 $\Omega$ are connected in Series, so the net resistance:

$\dashrightarrow \: \: \sf R_{n} = R_{1} + R_{2} + R_{3}$

$\dashrightarrow \: \: \sf R = 5 + 10 + 15$

${ \pink{\dashrightarrow \sf \: \: { \underbrace{R = 30 \: \Omega}}}}$

According to ohm's law:

$\dashrightarrow \sf\: \: V = IR$

$\dashrightarrow \sf \: \: I = \dfrac{V}{R}$

On substituting resultant voltage (V) as 10 V and resultant resistant, as 30 ${\pmb{\sf{\Omega}}}$ we get:

$\dashrightarrow \sf \: \: I = \dfrac{10V}{30\Omega}$

${ \pink{\dashrightarrow \sf \: \: { \underbrace{I = 0.33 A}}}}$

$\therefore$ The electric current passing through the above circuit when the key is closed will be <u>0.33 A</u>

4 0

2 years ago

Read 2 more answers

One hazard of space travel is the debris left by previous missions. There are several thousand objects orbiting Earth that are l

MariettaO [177]

Answer:

F = 6666.7 N

Explanation:

Given that,

Mass of a chip, m = 0.1 mg

Initial speed, u = 0

Final speed, $v=4\times 10^{3}\ m/s$

Time of collision, $t=6\times 10^{-8}\ s$

We know that,

Force, F = ma

Put all the values,

$F=\dfrac{m(v-u)}{t}\\\\F=\dfrac{0.1\times 10^{-6}\times (4\times 10^3-0)}{6\times 10^{-8}}\\\\F=6666.7\ N$

So, the required force is 6666.7 N.

3 0

3 years ago

Determine the weight in newtons of a woman whose weight in pounds is 157. Also, find her mass in slugs and in kilograms. Determi

DerKrebs [107]

Answer:

Weight of the woman in Newton

$x = 698.6 \ N$

Mass of the woman in slug

$Mass = 4.86 \ slug$

Mass of the woman in kg

$Mass = 16 \ kg$

My weight in Newton

$W = 784 \ N$

Explanation:

From the question we are told that

The weight of the woman in pounds is $W = 157 \ lb$

Converting to Newton

1 N = 0.22472 lb

x N = 157

=> $x = \frac{157 * 1}{0.22472}$

=> $x = 698.6 \ N$

Obtaining the mass in slug

$Mass = \frac{W}{g}$

Here $g = 32.2 ft/s^2$

So

$Mass = \frac{157 }{32.2}$

$Mass = 4.86 \ slug$

Obtaining the mass in kilogram

$Mass = \frac{W}{g}$

Here $g = 9.8 \ m/s$

So

$Mass = \frac{157 }{9.8}$

$Mass = 16 \ kg$

Generally weight is mathematically represented as

$W = m * g$

Given that my mass is 80 kg then my weight is

$W = 80 *9.8$

$W = 784 \ N$

6 0

3 years ago

How much energy (in Joules) is released when 12.0 g of water cools from 20.0 °C to 11.0 °C? This is a grade 10 question from the

KATRIN_1 [288]

Answer: - 452.088joule

Explanation:

Given the following :

Mass of water = 12g

Change in temperature(Dt) = (11 - 20)°C = - 9°C

Specific heats capacity of water(c) = 4.186j/g°C

Q = mcDt

Where Q = quantity of heat

Q = 12g × 4.186j/g°C × - 9°C

Q = - 452.088joule

7 0

3 years ago