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3 years ago

If an ice cube melts at 0°C, but water also freezes at 0°C,

1 answer:

3 0

The air heat melts the ice cube due to a different change in the temperature so the ice cube will stay the same at 0•C it’s just gonna melt because of the temperature change

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A transformer connected to a 120-V (rms) ac line is to supply 12,500 V (rms) for a neon sign. To reduce shock hazard, a fuse is

Tamiku [17]

Answer:

a) 104

b) 106

c) 884 mA

Explanation:

The ratio of the transformer is given by:

$N=\frac{V_{out}}{V_{in}}=\frac{12500V}{120V}=104$

We need to know the current in the primary in order to obtain the power applied.

$I_1=I_2*N=8.50mA*104=884mA\\\\P=I*V=884*10^{-3}A*120V=106W\\$

The current rating of the fuse is the current on the primary, 884mA as we calculated before in order to obtain the power.

4 0

3 years ago

As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff springs arr

zubka84 [21]

Answer:

$894.12\ \text{N}$

$284.013\ \text{J}$

Explanation:

U = Energy = 76 J

x = Displacement of spring = 0.17 m

k = Spring constant

Energy is given by

$U=\dfrac{1}{2}kx^2\\\Rightarrow k=\dfrac{2U}{x^2}\\\Rightarrow k=\dfrac{2\times 76}{0.17^2}\\\Rightarrow k=5259.51\ \text{Nm}$

Force is given by

$F=kx\\\Rightarrow F=5259.51\times 0.17\\\Rightarrow F=894.12\ \text{N}$

The magnitude of force must you apply to hold the platform is $894.12\ \text{N}$ .

Now $x=0.17+0.2=0.37\ \text{m}$

$U=\dfrac{1}{2}kx^2\\\Rightarrow U=\dfrac{1}{2}\times 5259.51\times 0.37^2\\\Rightarrow U=360.013\ \text{J}$

Additional energy

$360.013-76=284.013\ \text{J}$

8 0

2 years ago

you lift a 30 N crate 2 meters onto a shelf. it takes you 5 seconds to accomplish this. how much gravitional potential energy do

Dmitrij [34]

Gravitational potential energy is equal to force times height. That's 30 x 2 = 60 Joules. It makes no difference how fast or how slow you do the lift.

5 0

3 years ago

8. Where are the ribosomes usually located in plant and animal cells?

professor190 [17]

Answer:

Ribosomes are found 'free' in the cytoplasm or bound to the endoplasmic reticulum (ER) to form rough ER.

5 0

3 years ago

Peter throws a snowball at his car parked in the driveway. The snowball disintegrates as it hits the car. By Newton’s third law,

tamaranim1 [39]

"he force exerted by the car is more than the force exerted b y the snowball" is the one among the following that can be said <span>about the magnitude of the forces exerted by the snowball and the car. The correct option among all the options that are given in the question is the first option or option "A". I hope it helps you.</span>

3 0

3 years ago

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