Assessment on Work, Power, and Simple Machines

When measuring and recording mass in science which SI units should you use?

• Meter

• Liter

• Gram

• Celcius

Answer explanation

In science, mass is measured in grams (g), which is the correct SI unit for this purpose. Other options like meter, liter, and Celsius are used for measuring length, volume, and temperature, respectively.

During the course of a day you exhale 600 liters of carbon dioxide, how many decaliters does this represent?

• 600000 daL

• 6 daL

• 6000 daL

• 60 daL

Answer explanation

To convert liters to decaliters, divide by 10. Thus, 600 liters ÷ 10 = 60 daL. Therefore, the correct answer is 60 daL.

Based on the graph below, what is population of this area in the year 2000?

• 400 people

• 0 people

• 670 people

• 300 people

Answer explanation

The graph indicates that the population in the year 2000 is represented by the value at that point, which is 300 people. Therefore, the correct answer is 300 people.

If your cat has a mass of 3.6 kg how many milligrams does this represent?

• 0.00036 mg

• 36 mg

• 360 mg

• 3600000 mg

Answer explanation

To convert kg to mg, multiply by 1,000,000. Thus, 3.6 kg = 3.6 x 1,000,000 mg = 3,600,000 mg. The correct answer is 3600000 mg.

(True or false) Scientists around the world use the SI unit second for time.

• False

• True

Answer explanation

True. The SI unit for measuring time is the second, and it is universally used by scientists worldwide for consistency in scientific communication and calculations.

The slope of the line below represents which kind of relationship:

• Positive relationship

• Negative relationship

• Zero relationship

• Toxic relationship

Answer explanation

The slope of the line indicates a positive relationship, meaning that as one variable increases, the other variable also increases. This is characteristic of a positive correlation between the two variables.

Which number in standard notation represents 4.1 x (10^3)?

• 41000

• .0041

• 4100

• 4.1

Answer explanation

To convert 4.1 x (10^3) to standard notation, multiply 4.1 by 1000, which equals 4100. Therefore, the correct answer is 4100.

What is the main difference between a scientific theory and a scientific law?

• Laws are more important than theories

• Theories describe what happens, while Laws explain why

• Laws describe what happens, while theories explain why

• Theories are always proven true

Answer explanation

The main difference is that laws describe what happens in nature, often in a concise mathematical form, while theories explain why those phenomena occur, providing a broader understanding of underlying principles.

A student wants to test if the diameter of her straw in the balloon car affects the speed. She builds 5 identical cars but changes the diameter of the straw on each one. She then tests and calculates the speed of each one. In this experiment which of the following is the dependent (responding) variable?

• The shape of the balloon

• The distance they travel

• The speed of the car

• The diameter of the straws

Answer explanation

The speed of the car is the dependent variable because it is what the student measures to see how it responds to changes in the diameter of the straw. The other options are either constants or not being measured.

What is the role of control variables in an experiment?

• They are changed throughout the experiment

• They measure the experiment's outcome

• They remain constant to ensure valid results

• They replace the independent variable

Answer explanation

Control variables remain constant to ensure valid results by eliminating potential confounding factors. This allows the experiment to accurately measure the effect of the independent variable on the dependent variable.