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3 years ago

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A man is lifting a piano that weighs 800 N through a distance of 10 meters using a pulley system. The man pulls the rope a total

distance of 100m. What force does the man need to apply to the rope?

1 answer:

Flauer [41]3 years ago

3 0

Answer:

The force the man applied is 80 N

Explanation:

weight of the load, L = 800 N

distance traveled by the load, a = 10 m

distance traveled by the effort, b = 100 m

Output work = load x distance moved by the load

Output work = 800 x 10 = 8000 J

Input work = Effort x distance moved by effort

Input work = Effort x 100 m

Assuming an ideal machine; no friction effect, the input work will be equal to output work.

Effort x 100 m = 8000 J

Effort = 8000 / 100

Effort = 80 N

Therefore, the force the man applied is 80 N

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A stone was dropped off a cliff and hit the ground with a speed of 88 ft/s . What is the height of the cliff? (Use 32 ft/s 2 for

bulgar [2K]

To solve this problem we will apply the linear motion kinematic equations, which describe the change in velocity, depending on the acceleration and the distance traveled, that is,

$v_f^2 = v_i^2 +2ah$

Where,

$v_f$ = Final Velocity

$v_i$ = Initial Velocity

a = Acceleration

h = height

Our values are given as,

$v_f = 88 ft/s\\v_i = 0 ft /s\\a = 32 ft/s^2\\$

Replacing we have,

$vf^2 = vi^2 + 2*a*h$

$88^2 = 0 + 2*32*h$

$h= 121 ft$

Therefore the height of the cliff is 121ft

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3 years ago

A neutral atom of uranium (U) has 146 neutrons and a mass number of 238. How many protons does it have?

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Answer:

92 protons

Explanation:

The mass number is 238 , so the nucleus has <u>238 particles</u> in total, including <u>146 neutrons</u>. So to calculate the number of neutrons we have to subtract: 238 − 146 = 92

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3 years ago

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When is the average velocity of an object equal to the instantaneous velocity?

atroni [7]

Answer:

Average velocity of an object is equal to the instantaneous velocity when it's acceleration is zero.

Explanation:

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3 years ago

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2 years ago

The capacitor can withstand a peak voltage of 590 volts. If the voltage source operates at the resonance frequency, what maximum

kirill115 [55]

Answer:

The maximum voltage is 41.92 V.

Explanation:

Given that,

Peak voltage = 590 volts

Suppose in an L-R-C series circuit, the resistance is 400 ohms, the inductance is 0.380 Henry, and the capacitance is $1.20×10^{-2}\ \mu F$ .

We need to calculate the resonance frequency

Using formula of frequency

$f=\dfrac{1}{2\pi\sqrt{LC}}$

Put the value into the formula

$f=\dfrac{1}{2\pi\sqrt{0.380\times1.20\times10^{-8}}}$

$f=2356.88\ Hz$

We need to calculate the maximum current

Using formula of current

$I=\dfrac{V_{c}}{X_{c}}$

$I=2\pi\times f\times C\times V_{c}$

$I=2\pi\times2356.88\times1.20\times10^{-8}\times590$

$I=0.1048\ A$

Impedance of the circuit is

$z=\sqrt{R^2+(X_{L}^2-X_{C}^2)}$

At resonance frequency $X_{L}=X_{C}$

$Z=R$

We need to calculate the maximum voltage

Using ohm's law

$V=I\times R$

$V=0.1048\times400$

$V=41.92\ V$

Hence, The maximum voltage is 41.92 V.

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3 years ago