Criteria Design 1 Design 2 Design 3 Design 4

Question

Water Temperature (°C) 18 30 22 22
Amount of Water 20 ml 20 ml 10 ml 45 ml
Condition of Tablet whole whole crushed broken into 4 pieces
Distance (cm) 48 30 18 50
Speed (cm/s) 12cm/s 15cm/s 6cm/s 20cm/s

Science students were learning about Newton's laws of motion. Their teacher challenged them to build a gas-propelled boat using a film canister. The students had to design the propelled boat to produce enough thrust to win a boat race. The boats would be judged on the distance traveled and the speed of the boat. To do this, the students had to understand chemical reactions, the rate of reactions, and Newton's laws of motion. In real life, when propellants burn, pressure is created. Releasing this pressure through a small opening generates thrust that can be used to move objects. In this case, pressure is generated from the gas released as an Alka-Seltzer tablet undergoes a reaction in water. The gas is released out the back of the canister, forcing the boat to move in the opposite direction.

Each student group was given the following:
For each group:
2 Alka-Seltzer® antacid tablets
1/2 sheet of blank paper
1 film canister (with hole in lid)
3-4" (2 cm) piece of foam for a fin

The students all brainstormed and came up with variables that might be manipulated to win the boat challenge. The group data is compiled in the data table.
Using the students' experiment and data, can you identify the statements that are correct?
Responses
A The greater the gas build up in the canister, the greater the thrust force.The greater the gas build up in the canister, the greater the thrust force.
B There was a direct relationship between water temperature and the force created to move the boat.There was a direct relationship between water temperature and the force created to move the boat.
C The boat's forward motion in this experiment illustrates Newton's 3rd law of motion.The boat's forward motion in this experiment illustrates Newton's 3rd law of motion.
D Team #3's manipulated variables produced the least amount of force.Team #3's manipulated variables produced the least amount of force.
E Team #1 travelled faster than Team #2, but a shorter distance. This contradicts Newton's 2nd law of motion, F = ma.

Answer 1

Let's analyze each statement in light of the information provided about the gas-propelled boats considering Newton's laws of motion and the relationship between various manipulated variables.

A. The greater the gas buildup in the canister, the greater the thrust force.
Correct. This statement is true because increasing the amount of gas buildup in the canister would increase pressure and consequently increase thrust, as more gas means that more pressure can be released out of the opening.

B. There was a direct relationship between water temperature and the force created to move the boat.
Not necessarily correct. While water temperature can affect reaction rates (warmer water generally speeds up reactions), the data provided doesn't explicitly show a clear direct relationship between temperature and force created. Without specific force measurements corresponding to each temperature condition, this statement cannot be confirmed.

C. The boat's forward motion in this experiment illustrates Newton's 3rd law of motion.
Correct. This statement is true because Newton's 3rd Law of Motion states that for every action, there is an equal and opposite reaction. The boat moves forward while gas is expelled backward, demonstrating this principle.

D. Team #3's manipulated variables produced the least amount of force.
Correct. Given that Team #3 used a crushed tablet in 10 ml of water and the slowest speed of 6 cm/s compared to others with larger amounts of water or whole tablets, it's reasonable to conclude that it produced the least thrust or force, especially since the other designs typically provide more effective reactions due to higher water and whole tablet use.

E. Team #1 travelled faster than Team #2, but a shorter distance. This contradicts Newton's 2nd law of motion, F = ma.
Not correct. While it's true that Team #1 had a faster speed (12 cm/s) compared to Team #2 (15 cm/s), the distance traveled is not provided in the data, so we cannot definitively say that Team #1 traveled a shorter distance. Furthermore, Newton's 2nd Law (F = ma) describes the relationship between mass, acceleration, and force but does not necessarily imply a contradiction unless there’s a clear reason based on mass and acceleration data, which is not adequately presented here.

In summary, the correct statements are A, C, and D. Statements B and E are not clearly supported by the provided data.