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SashulF [63]
3 years ago
10

An 84% efficient single pulley is used to lift a 230 kg piano 3.5 m. How much work must be input?

Physics
1 answer:
Sati [7]3 years ago
3 0

Answer:

35%

Explanation:

win

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A conductor of radius r, length and resistivity ρ has resistance r. what is the new resistance if it is stretched to 4 times its
max2010maxim [7]
The resistance of a conductor is given by
R= \frac{\rho L}{A}
where L is the length of the wire, \rho the resistivity of the material and A the cross-sectional area.

We can see that if all the other quantities do not change, if the new length of the conductor is 4 times the original length: L'=4 L, then the new resistance is also 4 times the original value:
R'= \frac{\rho L'}{A}= \frac{\rho 4 L}{A}=4  \frac{\rho L}{A}=4 R
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3 years ago
A thunderclap sends a sound wave through the air and the ocean below. The
marysya [2.9K]

Answer:

C. 14.93 m

Explanation:

The given frequency of the wave, f = 100 Hz

The given equation for the wave speed, <em>v</em>, is presented as follows;

v = f × λ

The speed of sound in water, v = 1,493 m/s

Therefore, we get;

The wavelength, λ = v/f

∴ λ = 1,493 m/s/(100 Hz) = 14.93 m

The wavelength, λ = 14.93 m.

8 0
3 years ago
What is elasticity in polymer generally related to?
Andrej [43]
The elasticity of a polymer is primarily due to the structure of the molecule and the cross-linking between strands. Hydrogen bonding is a contributor to the shape of the molecule, but not a major player in terms of elasticity. We would have to answer "false".
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3 years ago
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A 20.0-N weight slides down a rough inclined plane which makes an angle of 30 degree with the horizontal. The weight starts from
Ulleksa [173]

Answer:

1270.64\ \text{J}

Explanation:

m = Mass of object = \dfrac{mg}{g}

mg = Weight of object = 20 N

g = Acceleration due to gravity = 9.81\ \text{m/s}^2

v = Final velocity = 15 m/s

u = Initial velocity = 0

d = Distance moved by the object = 150 m

\theta = Angle of slope = 30^{\circ}

f = Force of friction

fd = Work done against friction

The force balance of the system is

\dfrac{1}{2}m(v^2-u^2)=(mg\sin\theta-f)d\\\Rightarrow \dfrac{1}{2}mv^2=mg\sin\theta d-fd\\\Rightarrow fd=mg\sin\theta d-\dfrac{1}{2}mv^2\\\Rightarrow fd=20\times \sin 30^{\circ}\times 150-\dfrac{1}{2}\times \dfrac{20}{9.81}\times 15^2\\\Rightarrow fd=1270.64\ \text{J}

The work done against friction is 1270.64\ \text{J}.

8 0
3 years ago
If an astronaut has a mass of 80kg on earth, what is their mass on the moon?
stealth61 [152]

Answer:

130 N basically

Explanation:

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