PMA Review

#16 - If I roll a ball down a hill, which of the following describes what happens to the ball?

• Q - Friction helps the ball move down hill

• R - Gravity pulls the ball down hill

• S - Air resistance will make the ball slow down

• T - Friction is greater the force of gravity

#17 - What is a control group in an experiment?

• E - The control group represents what would happen without the change scientists are testing.

• F - The control group is the group that we make the most changes to

• G - The control group is like a model, scientist use it to study things that are not easily accessible

• H - The control group is what you are measuring

# 18 - Why is a control group important?

• I - Because a scientists must form a prediction to see if their results are valid.

• J - Because a scientist must know which variable is being used for a model

• K - Because scientists must observe data to make a conclusion based on evidence

• L - Because scientists must know what normally occurs so they can compare this to what they are testing.

#19 - Explain what is going to happen in this photo

• L - The forces are unbalanced on the sides so it will move to the right.

• M - All of the forces are balanced so there will be no movement

• N - The ball will move up because there are equal forces on the left and right but unbalanced forces up and down. Since the force is greater pushing up, the ball will move up.

• O - The ball will move down because it has less force.

# 20 - Sofia pushed with equal force on two objects. Object 1 has twice as much mass as Object 2. Which of the following statements is true?

• C - Object 2 will move faster than Object 1

• D - Both objects will remain still

• E - Object 1 will move faster will move faster than Object 2

• F - Both objects will move at the same time

#21 - When conducting and investigation, a scientist's main goal should be which of the following?

• E - Scientists should try to answer questions about the natural world

• F - Scientists should follow the same steps of the scientific method for every investigation

• G - The scientists should try to be famous for his work.

• H - The scientists should include his opinions in the results.

#22 - While on a camping trip, Mary and Catie are traveling in a boat on a river. On their trip, the river's current carries them along at a speed of 5 meters per second (m/s). They do not need to row because the current is carrying them in the direction they need to go. If no other forces are acting on the boat, which of these statements describes the motion of the boat as it travels?

• W - It speeds up

• X - It slows down

• Y - It stays the same

• Z - It changes direction