In the same science fair,Tina ask the question "does caffeine increase the heart rate of an earthworm?" In test 1,she measures the heart rate by looking at the earthworm under a microscopes, the heart rate if 50 beats per minute. In test 2,she places a few drops of caffeine on the earthworms skin and measures the rate again.in this test the heart rate is 68beats per minuteWhat is the independent variable in this experiment
What is the dependent variable in this experiment
Tina's experiment should have included a hypothisis .in a complete sentence,suggest a hypothesis for Tina's experiment

Answers

Answer 1

Answer: The independent variable is the one that does not change depending on other variables - so here it would be the presence or the absence of caffeine - this is dependent on Tina's actions, but not on other variables in the experiment. The dependent variable is the heart rate - it is assumed to depend on the presence or absence of caffeine. A hypothesis could be that "Caffeine causes an increase of heart rate in earthworms" - and this hypothesis is what the experiment is testing.

Related Questions

Exactly 15.0 g of a substance can be dissolved in 150.0 g of water what is the solubility of the substance in grams per 100 g of water
Ionic bonds result from high electronegativity differences. a. True b. False
Based on the Arrhenius theory, when potassiumhydroxide dissolves in water, the only negativeion in the aqueous solution is(1) O2 (aq) (3) H (aq)(2) OH2 (aq) (4) OH (aq)
How do valence electrons affect reactivity?
The reaction below demonstrates which characteristic of a base?CuSO4(aq)+2NaOH(aq)->Cu(OH)2(s)+Na2SO4the ability of bases to release sodium ions into solutionthe ability of bases to release hydrogen ions into solutionthe ability of a base to react with carbonate or bicarbonatethe ability of a base to react with a soluble metal salt

Which foods contain acids? Check all that apply:a.) limes b.) sourdough bread c.) water d.) sugar e.) honey f.) milk g.) lemons h.) tomatoes

Answers

Answer:

Limes

Lemons

Tomatoes

Explanation:

They all contain citric acid - the others are basic

Answer:

a.) Limes

b.) Sourdough bread

g.) Lemons

h.) Tomatos

Explanation:

I found a type of rock in the woods it's kinda rough black with some purple like a lavender purple and i can break it into pieces what could it be?

Answers

It could be a lump of coal.
Since you can break pieces off, maybe charcoal ... the real thing, not a "briquet".
Do your hands get all black when you handle it ?

An experiment applies heat to a substance and produces a gas that is a new and different substance. Choose the true statement.A. This represents a physical change only.
B. This represents a chemical change only.
C. This represents both a physical and a chemical change.
D. This represents neither a physical change nor a chemical change.

Answers

I believe it is C; reasoning being that the hint for physical change is," the producing of a gas," chemical "that's new and diff. substance. "

a. How much energy is needed to raise the temperature of a 75 g sample of aluminum from 22.4°C to 94.6°C?

Answers

To calculate the energy required to raise the temperature of a substance, you can use the formula:

Q = m * c * ΔT

Where:
Q is the energy (in joules)
m is the mass of the substance (in grams)
c is the specific heat capacity of the substance (in joules per gram-degree Celsius)
ΔT is the change in temperature (in degrees Celsius)

For aluminum, the specific heat capacity is approximately 0.897 J/g°C.

Given:
Mass of aluminum (m) = 75 g
Specific heat capacity of aluminum (c) = 0.897 J/g°C
Change in temperature (ΔT) = 94.6°C - 22.4°C = 72.2°C

Substituting the values into the formula:

Q = 75 g * 0.897 J/g°C * 72.2°C

Calculating the result:

Q = 4846.35 J

Therefore, approximately 4846.35 joules of energy are needed to raise the temperature of a 75 g sample of aluminum from 22.4°C to 94.6°C.

Introduction:

Understanding the amount of energy required to change the temperature of a substance is fundamental in many fields, from chemistry and physics to engineering and everyday applications. In this case, we're looking at how much energy it takes to heat a 75 g sample of aluminum.

Specific Heat Capacity of Aluminum:

To determine the energy required, we first need to consider the specific heat capacity of aluminum. The specific heat capacity (c) is a unique property of each material and represents the amount of heat energy needed to raise the temperature of 1 gram of that substance by 1 degree Celsius (or 1 Kelvin). For aluminum, the specific heat capacity (c) is approximately 0.897 J/g°C (joules per gram per degree Celsius).

Mass of the Sample:

The next piece of the puzzle is the mass of the aluminum sample. You mentioned that it's 75 grams, so we'll use that value in our calculations.

Change in Temperature:

We're looking to raise the temperature of the aluminum from 22.4°C to 94.6°C. To find the change in temperature (ΔT), we subtract the initial temperature from the final temperature:

ΔT = 94.6°C - 22.4°C = 72.2°C

Calculating the Energy:

Now, we can use the specific heat capacity formula to calculate the energy (Q) needed to raise the temperature of the aluminum sample:

Q = m * c * ΔT

Where:

Q is the energy in joules (J).

m is the mass of the sample (75 g).

c is the specific heat capacity of aluminum (0.897 J/g°C).

ΔT is the change in temperature (72.2°C).

Plugging in these values:

Q = 75 g * 0.897 J/g°C * 72.2°C

Q ≈ 4863.15 J

Conclusion:

Therefore, approximately 4863.15 joules of energy are needed to raise the temperature of a 75 g sample of aluminum from 22.4°C to 94.6°C. This calculation is essential in various scientific and practical applications, from cooking to materials engineering, and helps us understand the energy requirements for temperature changes in different substances.

A cluster of billions of atoms that all have magnetic fields lined up in the same way is known as aa. magnetic field line.
b. magnetic pole.
c. magnetic domain.
d. permanent magnet.
The region around a magnet where the magnetic force is exerted is known as its
a. magnetic pole.
b. lodestone.
c. magnetic field.
d. magnetic domain.

Answers

A cluster of billions of atoms that all have magnetic fields lined up in the same way is known as a

The answer is letter C. Magnetic domain.

The region around a magnet where the magnetic force is exerted is known as its
The answer is letter C. Magnetic field.

Answer:

i think its b tell me if im wrong if i am sorry

Explanation:

. Find the mass of 0.159 mol silicon dioxide.

Answers

One mole of any element contains 6.022×10²³ atoms which is also called Avogadro number. The mass of 0.159 mole silicon dioxide. is 9.55g.

What is mole?

The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity of amount of substance. It measure the number of elementary entities of a given substance that are present in a given sample.

Mathematically,

mole =given mass ÷ Molar mass

First of all we find the molar mass of silicon oxide

Molar mass of silicon oxide= atomic mass of silicon+2×molar mass of oxygen

Molar mass of silicon oxide=28.0855+2×16

Molar mass of silicon oxide=60.08 g/mol

Substituting the values in fisrt equation we get

0.159 mol=given mass÷60.08 g/mol

0.159 mole x 60.08 g/mol=mass

9.55g=mass of silicon oxide

Therefore the mass of 0.159 mol silicon dioxide. is 9.55g.

To know more about mole, here: