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dimulka [17.4K]
3 years ago
10

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

rench from the top of the tower. If the average force of air resistance is 0.141n , what will the kinetic energy of the wrench be when it hits the water
Physics
1 answer:
yaroslaw [1]3 years ago
7 0

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.

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What is the frequency of a wave with a wavelength of 15 m and a wavespeed of<br> 300 m/s?
STatiana [176]

Answer: f=20 (i think)

Explanation:

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300/15= 20

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Help ASAP please (: The waves with the MOST energy have
tino4ka555 [31]

Answer: C

high; large

Explanation:

The wave energy is related to its amplitude and frequency.

The wave energy is proportional to the amplitude of the wave. So, wave with the most energy will have high amplitude.

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2 years ago
Which of the following will be attracted toward a positively charged cloth?
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2 years ago
A centrifugal pump is operating at a flow rate of 1 m3/s and a head of 20 m. If the specific weight of water is 9800 N/m3 and th
tamaranim1 [39]

Answer:

<em>The power required by the pump is nearly 230.588 kW</em>

Explanation:

Flow rate of the pump Q = 1 m^3/s

the head flow H = 20 m

specific weight of water γ = 9800 N/m^3

efficiency of the pump η = 85%

First note that specific gravity of water is the product of the density of water and acceleration due to gravity.

γ = ρg

where ρ is density. For water its value is 1000 kg/m^3

g is the acceleration due to gravity = 9.81 m/s^2

The power to lift this water at this rate will be gotten from the equation

P = ρgQH

but ρg = γ

therefore,

P = γQH

imputing values, we'll have

P = 9800 x 1 x 20 = 196000 W

But the centrifugal pump that will be used will only be able to lift this amount of water after the efficiency factor has been considered. The power of pump needed must be greater than this power.

we can say that

196000 W is 85% of the power of the pump power needed, therefore

196000 = 85% of P_{p}

where P_{p} is the power of the pump needed

85% = 0.85

196000 = 0.85P_{p}

P_{p} = 196000/0.85 = 230588.24 W

<em>Pump power = 230.588 kW</em>

3 0
3 years ago
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