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3 years ago

Adding heat to a liquid causes which of the following physical changes?

1 answer:

8 0

In almost every case in nature, adding heat to a liquid
causes the density of the liquid to decrease. That is,
when the liquid gets warmer, it expands and occupies
more space.

The one big exception to this rule is water !

Starting with a block of ice at zero°C (32°F), as the ice melts,
becomes water at zero°C, and all the way to 4°C (about 39°F),
its density increases all the way. That is, it shrinks and occupies
less volume as it goes from ice at zero°C to water at 4°C.

This sounds like an interesting but insignificant quirk ... until
you realize that if water didn't do this, then life on Earth would
be impossible !

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Which item is heavier, 50 kg of cotton or 50 kg of iron?

Kipish [7]

Answer:

They weight the same

Explanation:

6 0

3 years ago

Two in-phase loudspeakers that emit sound with the same frequency are placed along a wall and are separated by a distance of 2.4

NeX [460]

When person is observing destructive interference at 0.20 m distance from the equidistant position then we can say that path difference must be equal to half of the wavelength

now we will have

$\frac{\lambda}{2} = \frac{yd}{L}$

now we know that

y = 0.20 m

d = 2.4 m

L = 10 m

now here we have

$\frac{\lambda}{2} = \frac{0.20\times 2.4}{10}$

$\lambda = 0.096 m$

now frequency of wave is given as

$f = \frac{v}{\lambda}$

$f = \frac{343}{0.096} = 3573 Hz$

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3 years ago

A bus covers 10 km in 7 minutes. Find the speed of the bus in km/h

Shtirlitz [24]

Answer:

Explanation: so how many minutes are in an hour 60 right, and the bus travels 10km in 7 minutes right so use math the bus travels 14km in 10 minutes so the bus travels 98km in an hour

8 0

3 years ago

A man walks along a straight path at a speed of 4 ft/s. A searchlight is located on the ground 6 ft from the path and is kept fo

BARSIC [14]

We are given that,

$\frac{dx}{dt} = 4ft/s$

We need to find $\frac{d\theta}{dt}$ when $x=8ft$

The equation that relates x and $\theta$ can be written as,

$\frac{x}{6} tan\theta$

$x = 6tan\theta$

Differentiating each side with respect to t, we get,

$\frac{dx}{dt} = \frac{dx}{d\theta} \cdot \frac{d\theta}{dt}$

$\frac{dx}{dt} = (6sec^2\theta)\cdot \frac{d\theta}{dt}$

$\frac{d\theta}{dt} = \frac{1}{6sec^2\theta} \cdot \frac{dx}{dt}$

Replacing the value of the velocity

$\frac{d\theta}{dt} = \frac{1}{6} cos^2\theta (4)^2$

$\frac{d\theta}{dt} = \frac{8}{3} cos^2\theta$

The value of $cos \theta$ could be found if we know the length of the beam. With this value the equation can be approximated to the relationship between the sides of the triangle that is being formed in order to obtain the numerical value. If this relation is known for the value of x = 6ft, the mathematical relation is obtained. I will add a numerical example (although the answer would end in the previous point) If the length of the beam was 10, then we would have to