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2 years ago

By lubricating the pulley, the work needed was decreased from 50 J down to

Physics

1 answer:

Vinvika [58]2 years ago

8 0

Before lubrication:

$\tt \dfrac{40}{50}\times 100\%=80\%$

The efficiency of the pulley after lubrication becomes:

$\tt \dfrac{40}{44}\times 100\%=91\%$

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Find the resistance at 50°c of copper wire 2mm in diameter and 3m long

mr Goodwill [35]

0.0179 ohms for copper.

0.0184 ohms for annealed copper

Ď = R (A/l) where

Ď = electrical resistivity

R = electrical resistance of a uniform specimen

A = cross sectional area

l = length

Solve for R by multiplying both sides by l/A

R = Ď(l/A)

The cross section of the wire is pi * 1^2 mm = 3.14159 square mm = 3.14159e-6 square meters.

The length is 3 meters. So l/A = 3/3.14159e-6 = 9.5493e5

Ď for copper is 1.68e-8 so 1.68e-8 * 9.5493e5 = 1.60e-2 ohms at 20 C

But copper has a temperature coefficient (Î±) of 0.00386 per degree C.

So the resistance value needs to be adjusted based upon how far from 20 C the temperature is.

50 - 20 = 30 C

So 0.00386 * 30 = 0.1158 meaning that the actual resistance at 50 C will be 11.58% higher.

So 1.1158 * 0.016 = 0.0179 ohms.

If you're using annealed copper, the values for Ď and the temperature coefficient change.

Ď = 1.72e-8

Î± = 0.00393

Doing the math, you get

1.72e-8 * 9.5493e5 * (1 + 30 * 0.00393) = 0.0184 ohms

8 0

3 years ago

Para los siguientes cuerpos en movimiento, describa el tipo de trayectoria y represéntela con un dibujo.

Lorico [155]

Yo creo q es C x que ase sentido

3 0

3 years ago

Name the 9 types of energy

Ugo [173]

Hello There!

-Energy Is The Ability To Do Work-

Energy comes into different forms but they can all be placed in two different categories. These categories are "potential" which means stored energy and energy of position and "kinetic" which is the energy of motion.

POTENTIAL ENERGY Stored energy and the energy of position

CHEMICAL ENERGY Energy in the bonds of atoms and molecules

MECHANICAL ENERGY Energy stored in objects by tension

NUCLEAR ENERGY Energy stored in the nucleus of an atom

GRAVITATIONAL Energy that is stored in an object's height

ELECTRICAL ENERGY Delivered by tiny charged particles called electrons

KINETIC ENERY The energy of motion

THERMAL ENERGY The vibration and movement of atoms and molecules in substances.

RADIANT ENERGY Electromagnetic energy that travels in waves

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4 years ago

How long must a pendulum be to have a period of 4.6 5 on Neptune, where g = 11.15 m/s?

Anon25 [30]

Answer:

5.98 m

Explanation:

$T=2\pi \sqrt\frac{L}{g}$

$T^2=4\pi ^2L/g\\L = gT^2/(4\pi^2)$ = 11.15*4.6²/(4π²) = 5.98 m

5 0

2 years ago

A spaceship is traveling through deep space towards a space station and needs to make a course correction to go around a nebula.

expeople1 [14]

Answer:

Magnitude = 3.64 × $10^6$

စ = 43.9°

Explanation:

given data

ship to travel = 1.7 × $10^6$ kilometers

turn = 70°

travel an additional = 2.7 × $10^6$ kilometers

solution

we will consider here

Px = 1.7 × $10^6$

Py = 0

Qx =2.7 × $10^6$ cos(70)

Qy= 2.7 × $10^6$ sin(70)

so that

Hx = Px + Qx ............1

Hx = 2.62 × $10^6$

and

Hy = Py + Qy ..........2

Hy = 2.53 × $10^6$

so Magnitude = $\sqrt{((2.62 \times 10^6 )^2+(2.53 \times 10^6)^2)}$

Magnitude = 3.64 ×

so direction will be

tan စ = Hy ÷ Hx ......................3

tan စ = $\frac{2.53}{2.62}$

tan စ = 0.9656

စ = 43.9°

3 0

3 years ago