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3 years ago

When hot and cold air meet, the hot air rises to the top. What causes the hot air to rise???

1 answer:

3 0

Hot air rises because when you heat air (or any other gas for that matter), it expands. When the air expands, it becomes less dense than the airaround it. The less dense hot air then floats in the more dense cold air much like wood floats on water because wood is less dense than water.

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The image on the left shows the charges on a balloon after it’s been rubbed with a wool cloth. The image on the right is a piece

taurus [48]

When wool is rubbed with a balloon, the wool is left with a positive charge as electrons have travelled from the wool to the balloon which means the balloon now has a negative charge.

Now that the balloon has a negative charge, you need to know:
The tissue paper originally contains electrons and protons
The fact that the balloon has a negative charge, it will ATTRACT protons because protons are POSITIVE and electrons are NEGATIVE.
So once they are attracted, they will move closer to one another.

3 0

2 years ago

Read 2 more answers

Water runs out of a horizontal drainpipe at the rate of 135 kg/min. It falls 3.1 m to the ground. Assuming the water doesn't spl

Arlecino [84]

Answer:

The average force exerted by the water on the ground is 17.53 N.

Explanation:

Given;

mass flow rate of the water, m' = 135 kg/min

height of fall of the water, h = 3.1 m

the time taken for the water to fall to the ground;

$h = ut + \frac{1}{2}gt^2\\\\h = 0 + \frac{1}{2}gt^2\\\\t = \sqrt{\frac{2\times 3.1}{9.8} } \\\\t = 0.795 \ s$

mass of the water;

$m = m't\\\\m = 135 \ \frac{kg}{min} \ \times \ 0.795 \ s \ \times \ \frac{1 \ \min}{60 \ s} \ = 1.789 \ kg$

the average force exerted by the water on the ground;

F = mg

F = 1.789 x 9.8

F = 17.53 N

Therefore, the average force exerted by the water on the ground is 17.53 N.

7 0

3 years ago

On a road trip, a driver achieved an average speed of (48.0+A) km/h for the first 86.0 km and an average speed of (43.0-B) km/h

Bond [772]

A = 15, B = 1
48 + 15 = 63 for the first 86km
43 - 1 = 42 for the remaining 54 km
time = distance/speed
t1 = 86/63 = 1.3651hours
t2 = 54/42 = 1.2857hours
speed = distance/time
s = 140/2.6508
average speed = 52.8km/h

4 0

3 years ago

Why do elements in groups share more chemical properties than elements in a period

lyudmila [28]

Answer:

Elements in a period share the highest unexcited electron energy level. There are more elements in some periods than others because the number of elements is determined by the number of electrons allowed in each energy sub-level.

Explanation:

3 0

3 years ago

. Suppose you walk 18.0 m straight west and then 25.0 m straight north. How far are you from your starting point? What is your d

Scorpion4ik [409]

Answer:

Explanation:

The total distance is how far you walk from the starting point.

Distance through west = 18.0m

Distance through north = 25.0m

Total distance covered = 18.0+25.0m

Total distance covered = 43.0m

This means that I am 43.0m from the starting point

Displacement is the distance covered in a specified direction. The displacement will be gotten using the Pythagoras theorem as shown:

$d^2 = 25^2 + 18^2\\d^2 = 625+324\\d^2 = 949\\d = \sqrt{949}\\ d = 30.81m$

The direction of your displacement is 30.81m

Direction is gotten according to the formula;

$\theta = tan ^{-1}{\frac{y}{x} }\\\theta = tan ^{-1}{\frac{25}{-18} }\\\theta = tan ^{-1}-1.3889}\\\theta = -60.27^0\\\theta = 180-60.27\\\theta = 119.7^0$

Note that the direction to the west is negative, that is why the x is -18.0m

5 0

2 years ago