COGNIA_ FÍSICA_ PARCIAL 1

A student performs an investigation to study Newton’s second law:

force = mass × acceleration.

Two marbles of different masses are released at the top of a ramp and roll down the ramp. The student measures the distance each marble travels. The procedure is repeated three times and the average distance traveled by each marble is calculated. The summarized data are shown in the table.

Which of the following is the independent variable in the investigation?

• ramp height

• marble mass

• number of tests

• distance traveled by marble

Two students are investigating the effect of forces on the motion of an object. The two students each push on a box, as shown in the picture.

Even though the students are pushing the box very hard, the box does not move. Describe one way the students could make the box move. Explain why this would move the box.

An educational-supply company developed a model rocket to sell to school districts. Science teachers use the rocket to help students investigate motion. The rocket has a cargo area designed to hold water. Water can be added to or removed from the cargo area.

When launched with an empty cargo area, the rocket is designed to reach a maximum vertical height of 10 meters. A school district wants to buy rockets that can reach only 7 meters in vertical height. The company cannot change the force applied by the rocket’s engine or the shape of the rocket.

Describe how the company could investigate a solution to this problem. Explain why the investigation is reasonable based on Newton’s laws of motion.

Molly is investigating the change in motion of an object. She kicks a soccer ball that is sitting on a soccer field three times. Molly changes the force of her kick each time and uses a device to measure the force. The data she collected are shown in the table.

a. Identify the independent and dependent variables of the investigation.

b. Describe two forces acting on the soccer ball when Molly kicks it.

c. Make a claim about the change in motion of an object that can be supported by evidence from the investigation and Newton’s laws of motion. Explain your reasoning.

Caleb is investigating the effect of friction on the motion of an object. He uses the following supplies for the investigation:

• a wooden block

• three ramps, each ramp is the same height and length but has a different surface (smooth wood, carpet, rough sandpaper)

• a stopwatch Caleb tests his hypothesis that the smooth wood ramp surface causes less friction than the carpet and that the carpet causes less friction than the rough sandpaper.

a. Describe a procedure using these supplies that Caleb may follow to test his hypothesis.

b. Explain the most likely reason Caleb uses the same wooden block for each test. c. Identify the independent and dependent variables for this investigation.

A group of students is investigating how a force applied to an object affects the motion of that object. The diagram shows the setup for the investigation. To create a force, the students add a weight to the weight holder and observe whether the cart moves. The students repeat this step five times, using a different amount of weight each time.

a. Identify the independent and dependent variables of this investigation.

b. Describe two forces acting on the cart. Include the direction of the force in your description.

c. Make a claim about the forces on the cart when the cart does not move. Support your claim using Newton’s laws of motion.