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3 years ago

When the temperature of ice-cold water is increased slightly, does it undergo a net expansion or net contraction?

1 answer:

4 0

From the freezing temperature up to about 4°C (39°F) the water CONTRACTS. That is, it becomes MORE dense. I think I read that water is the ONLY known substance whose solid phase floats in its liquid phase. That's why the cubes float in your soda and bergs float in the ocean. And if weren't so, then life on Earth would not be possible ! Oceans and lakes would freeze from the bottom up, ONE TIME, and then never thaw again.

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Martin is conducting an experiment. His first test gives him a yield of 5.2 grams. His second test gives him a yield of 1.3 gram

Bogdan [553]

Complete Question

Martin is conducting an experiment. His first test gives him a yield of 5.2 grams. His second test gives him a yield of 1.3 grams. His third test gives him a yield of 8.5 grams. On average, his yield is 5.0 grams, which is close to the known yield of 5.1 grams of substance. Which of the following are true?

A His results are accurate but not precise.

B His results are neither accurate nor precise.

C His results are both accurate and precise

D His results are precise but not accurate.

Answer:

Correct option is A

Explanation:

From the question we are told that

The yield of the first test $k = 5.2 \ g$

The yield of the second is $u = 1.3 \ g$

The third yield is $p = 8.5 \ g$

The average yield $A = 5.0 \ g$

The know yield is $A_S = 5.1 \ g$

From the data given we see that

$A_S \ne A$

Since his average yield is closer to the known yield then the answer is accurate

But since the yield for each test are not repeated the answer is not precise

So the answer is accurate but not precise

4 0

3 years ago

You throw a ball upward with an initial speed of 4.3 m/s. When it returns to your hand 0.88 s later, it has the same speed in th

djverab [1.8K]

Answer:

The acceleration is -9.8 m/s²

Explanation:

Hi there!!

When you throw a ball upward, there is a downward acceleration that makes the ball return to your hand. This acceleration is produced by gravity.

The average acceleration is calculated as the variation of the speed over time. In this case, we know the time and the initial and final speed. Then:

acceleration = final speed - initial speed/ elapsed time

acceleration = -4.3 m/s - 4.3 m/s / 0.88 s

acceleration = -9.8 m/s²

4 0

3 years ago

Lol somebody tell me the answer ill also give 5 stars

AnnyKZ [126]

Answer:

i believe it's carbon. i may be wrong. but i haven't done atoms in almost 2 years. sorry if it's wrong. :)) hava good day

Explanation:

4 0

3 years ago

Read 2 more answers

A 1.1 kg ball is attached to a ceiling by a 2.16 m long string. The height of the room is 5.97 m . The acceleration of gravity i

nydimaria [60]

1. -23.2 J

The gravitational potential energy of the ball is given by

$U=mgh$

where

m = 1.1 kg is the mass of the ball

g = 9.8 m/s^2 is the acceleration of gravity

h is the height of the ball, relative to the reference point chosen

In this part of the problem, the reference point is the ceiling. So, the ball is located 2.16 m below the ceiling: therefore, the heigth is

h = -2.16 m

And the gravitational potential energy is

$U=(1.1 kg)(9.8 m/s^2)(-2.16 m)=-23.2 J$

2. 41.1 J

Again, the gravitational potential energy of the ball is given by

$U=mgh$

In this part of the problem, the reference point is the floor.

The height of the ball relative to the floor is equal to the height of the floor minus the length of the string:

h = 5.97 m - 2.16 m = 3.81 m

And so the gravitational potential energy of the ball relative to the floor is

$U=(1.1 kg)(9.8 m/s^2)(3.81 m)=41.1 J$

3. 0 J

As before, the gravitational potential energy of the ball is given by

$U=mgh$

Here the reference point is a point at the same elevation of the ball.

This means that the heigth of the ball relative to that point is zero:

h = 0 m

And so the gravitational potential energy is

$U=(1.1 kg)(9.8 m/s^2)(0 m)=0 J$

4 0

4 years ago

When a star is in the main-sequence stage of its life, it is fusing __________ into ________

gizmo_the_mogwai [7]

Hydrogen into helium

7 0

3 years ago