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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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Answer:

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3 years ago
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A 35 kg box rests on the back of a truck. The coefficient of static friction bet?005 (part 1 of 2)A 35 kg box rests on the back
elena-14-01-66 [18.8K]

Answer with Explanation:

We are given that

Mass of box=35 kg

Coefficient of static friction between box and truck bed=0.202

Acceleration due to gravity=9.8 m/s^2

a.We have to find the force by which the box accelerates forward.

Force by which box accelerates=\mu mg=0.202\times 9.8\times 35

Force by which box accelerates=62.286 N

b.We have to find the maximum acceleration can the truck have before the box slides.

Force =friction force

ma=\mu mg

a=\mu g=9.8\times 0.202=1.9796 m/s^2

Hence, the truck can have maximum acceleration before the box slide=1.9796 m/s^2

3 0
3 years ago
Using a power supply, I place +1.00µC on one plate of a capacitor. A capacitor is a device for storing charge. I, then, connect
Paraphin [41]

Answer:

N=62421972534 electrons

Explanation:

The charge transferred charge Q= −10nC = -10*10-9 C

Charge of a electron : Q_{e}= -1,602*10^{-19}C

Number of electrons transferred:  N=\frac{Q}{Q_{e} }=(-10*10^{-9} )/(-1,602*10^{-19})=62421972534 electrons

5 0
3 years ago
4.72 A full-wave bridge-rectifier circuit with a 1-k load operates from a 120-V (rms) 60-Hz household supply through a 12-to-1 s
melisa1 [442]

Answer:

a) 12.74 V

b) Two pairs of diode will work only half of the cycle

c) 8.11 V

d) 8.11 mA

Explanation:

The voltage after the transformer is relationated with the transformer relationshinp:

V_o=Vrms*\frac{1}{12}\\V_o=10Vrms

the peak voltage before the bridge rectifier is given by:

V_{op}=Vo*\sqrt{2}\\V_{op}=14.14V

The diodes drop 0.7v, when we use a bridge rectifier only two diodes are working when the signal is positive and the other two when it's negative, so the peak voltage of the load is:

V_l=V_{op}-2(0.7)\\V_l=12.74V

As we said before only two diodes will work at a time, because the signal is half positive and half negative,so two of them will work only half of the cycle.

The averague voltage on a full wave rectifier is given by:

V_{avg}=2*\frac{V_l}{\pi}\\V_{avg}=8.11V

Using Ohm's law:

I_{avg}=\frac{V_{avg}}{R}\\\\I_{avg}=8.11mA

7 0
3 years ago
Until a train is a safe distance from the station, it must travel at 5 m/s. Once the train is on open track, it can speed up to
Harman [31]
Accelration=changespeed/changetime
changetime=8
changespeed=45-5=40
40/8=5

5m/s^2 is acceleration
4 0
2 years ago
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