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3 years ago

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Physics

2 answers:

AlekseyPX3 years ago

4 0

I believe it’s tackling but I’m not quite sure

dedylja [7]3 years ago

3 0

I would say swimming just from experience
But tackling just like football or wrestling can also be tiring

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The tops of the towers of the Golden Gate Bridge in San franciscoo , are 227 m above the water. Suppose a worker drops a 655 g w

yaroslaw [1]

Answer:

Kinetic energy is 1425.11 J.

Explanation:

Given:

Mass of the wrench is, $m=655\ g=0.655\ kg$

Height of fall is, $h=227\ m$

Force of resistance is, $F=0.141\ N$

Now, the total energy at the top is equal to the potential energy of the wrench at the top since the kinetic energy at the top is 0.

Now, potential energy at the top is given as:

$U=mgh\\U=0.655\times 9.8\times 227\\U=1457.113\ J$

Now, the potential energy at the top is converted to kinetic energy at the bottom and some energy is wasted in overcoming the resistance force by air.

Potential Energy = Kinetic energy + Energy to overcome resistance.

⇒ Kinetic energy = Potential Energy - Energy to overcome resistance.

Energy to overcome resistance force is the work done by the wrench against the resistance force and is given as:

$W_{res}=Fh=0.141\times 227=32.007\ J$

Therefore, Kinetic energy at the bottom is given as:

$K=U-W_{res}\\\\K=1457.113\ J - 32.007\ J\\\\K=1425.106\approx1425.11\ J$

Hence, the kinetic energy of the wrench be when it hits the water is 1425.11 J.

7 0

4 years ago

What is the resistance of : A) A 1.70 m long copper wire that is 0.700 mm in diameter? B) A 20.0 cm long piece of carbon with a

astra-53 [7]

Answer:

(I). The resistance of the copper wire is 0.0742 Ω.

(II). The resistance of the carbon piece is 1.75 Ω.

Explanation:

Given that,

Length of copper wire = 1.70 m

Diameter = 0.700 mm

Length of carbon piece = 20.0 cm

Cross section area $A = (2.00\times10^{-3})^2\ m$

(I). We need to calculate the area of copper wire

Using formula of area

$A=\pi r^2$

$A=3.14\times(\dfrac{0.700\times10^{-3}}{2})^2$

We need to calculate the resistance

Using formula of resistance

$R=\dfrac{\rho l}{A}$

Put the value into the formula

$R=\dfrac{1.68\times10^{-8}\times1.70}{3.14\times(\dfrac{0.700\times10^{-3}}{2})^2}$

$R=0.0742\ \Omega$

(II). We need to calculate the resistance

Using formula of resistance

$R=\dfrac{\rho l}{A}$

Put the value into the formula

$R=\dfrac{3.5\times10^{-5}\times20\times10^{-2}}{(2.00\times10^{-3})^2}$

$R=1.75\ \Omega$

Hence, (I). The resistance of the copper wire is 0.0742 Ω.

(II). The resistance of the carbon piece is 1.75 Ω.

8 0

4 years ago

A windmill is example of a a.generator b.resistor c.insulator d.motor

Alexandra [31]

The answer is a. generator!

4 0

3 years ago

Please answer! thank you!

lesantik [10]

Answer:

Maybe A.... I'm not sure

Explanation:

8 0

3 years ago

Read 2 more answers

I have an object that I want to know when it was made. I calculate that the object contains 0.12g of Iodine-131 but started with

Sav [38]

Answer: 71.72 days

Explanation:

This problem can be solved using the Radioactive Half Life Formula:

$A=A_{o}.2^{\frac{-t}{h}}$ (1)

Where:

$A=0.12 g$ is the final amount of Iodine-131

$A_{o}=60 g$ is the initial amount of Iodine-131

$t$ is the time elapsed

$h=8 days$ is the half life of Iodine-131

Knowing this, let's substitute the values and find $t$ from (1):

$0.12 g=(60 g)2^{\frac{-t}{8 days}}$ (2)

$\frac{0.12 g}{60g}=2^{\frac{-t}{8 days}}$ (3)

Applying natural logarithm in both sides:

$ln(\frac{0.12 g}{60g})=ln(2^{\frac{-t}{8 days}})$ (4)

$-6.21=-\frac{t}{8 days}ln(2)$ (5)

Finding $t$ :

$t=71.72 days$

7 0

4 years ago