Question

1. asa watches his mom rub soap on her finger to help her get a ring unstuck. he thinks that soap must reduce friction. he designs an investigation to test his theory. he pulls a weight across a board and records the force with a spring scale. he then puts soap on the board and pulls the weight again. which of the following variables is asa measuring?

(a) the speed with which the weight is pulled
(b) the amount of weight being pulled
(c) the force needed to pull the weight
(d) the type of surface the weight is being pulled across

1. erica is learning how to accurately read a thermometer. she places the following thermometer in the sun for 1 hour.

what temperature does erica read on the thermometer?
(f) 38° celsius
(g) 100° celsius
(h) 38° fahrenheit
(i) 105° fahrenheit
(image of thermometer with °c and °f scales)

1. different systems for making measurements use different units. which system of measurement is generally used by scientists?

(a) customary
(b) english
(c) imperial
(d) metric

1. joshua has been growing plants that receive ½ cup of water two times per week. now, he wants to see what happens to the plants when the amount of water is reduced, as shown in the chart.

(chart:
plant | amount of water
1 | no water
2 | ½ cup once every two weeks
3 | ½ cup once per week
4 | ½ cup two times per week
)
which plant is the control?
(f) 1
(g) 3
(h) 2
(i) 4

1. scientists want to determine if walls that are painted a certain color will raise a person’s blood pressure. they plan to set up four rooms. which variable should change in each room?

(a) the color used
(b) the type of room used
(c) the instruments used to test the blood pressure
(d) the amount of time the person spends in the room

Explanation:

Question 7

Asa uses a spring scale to record the force when pulling a weight, with and without soap on the board. The speed (A) isn't measured with a spring scale. The amount of weight (B) is constant (he pulls the same weight). The surface type (D) is changed (soap vs no soap), but he's measuring the force needed, not the surface. So the variable measured is the force to pull the weight.

Step1: Identify the scale.

The thermometer has °C (Celsius) on the left. The mercury level aligns with the 38 mark on the Celsius scale (since each major line is 10, and between 30 - 40, the level is at 38). The Fahrenheit scale is on the right, but the question's options for Celsius are F (38°C) and G (100°C). 100°C is boiling, not sun temp. So it's 38°C.

Step2: Confirm the reading.

The Celsius scale: from 0 - 50, each major division is 10, minor divisions (if any) but here the level is at 38 on the Celsius side. So the temperature is 38°C.

Scientists generally use the metric system (D) for measurements. Customary (A), English (B), and Imperial (C) are not the standard in scientific work. The metric system (SI units) is universal in science for consistency.

Answer:

C. the force needed to pull the weight

Question 8