Forces and Motion — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. A Grade 3 student drops a marble and a baseball from the same height with no air effect. Which hits the ground first?
A) The marble hits first
B) The baseball hits first
C) They hit the ground at the same time
D) Neither one falls
In Grade 3, ignoring air resistance, gravity makes all objects near Earth fall at the same rate, so they land together.
2. Why does a feather fall more slowly than a rock in real life?
A) Gravity is weaker on feathers
B) Air resistance pushes up on the feather more
C) Feathers are not pulled by gravity
D) Rocks have special magnets
In Grade 3 science, gravity pulls both, but air resistance slows the light feather more, so the rock reaches the ground first.
3. A ball is dropped from a Grade 3 classroom window. What makes it fall?
A) A magnet in the ground
B) The force of gravity from Earth
C) The wind only
D) Friction with the window
In Grade 3, gravity is the force that pulls all objects toward the center of Earth, including a dropped ball.
4. Two Grade 3 students drop different-sized rubber balls at the same time. What happens?
A) The heavier ball lands much sooner
B) The lighter ball lands much sooner
C) They land at about the same time
D) Both balls float in the air
In Grade 3 science, similar shapes fall at about the same rate because gravity acts the same on each, ignoring small air effects.
Part B: Fill in the Blank
Write the correct answer on each line.
1. The force that pulls objects toward Earth is called gravity.
In Grade 3, gravity is Earth's pull on all objects, and it is why a dropped ball falls to the ground.
2. Ignoring air, two objects dropped from the same height fall at the same rate.
In Grade 3 science, gravity pulls all objects equally near Earth, so they fall at the same rate without air effects.
3. A feather falls slowly because of air resistance pushing up on it.
In Grade 3, air resistance is a force from air that slows light, flat things like feathers as they fall.
4. Gravity always pulls objects toward the center of Earth.
In Grade 3 science, Earth's gravity pulls objects toward its center, which is why things fall downward.
5. Without gravity, a Grade 3 student's jump would never bring them back down.
In Grade 3, gravity pulls a jumper back down; without it, you would keep rising after you jump.