Force & Motion — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. A parachute opens above a toy figure as it falls. Why does the toy fall more slowly with the parachute?
A) The parachute adds weight to pull it down
B) Air pushes up on the parachute, slowing the fall
C) Gravity stops working when the parachute opens
D) The parachute makes the toy heavier than air
Air resistance pushes up on the parachute, balancing some of gravity's pull and slowing the fall.
2. On a swing set, a child needs a friend to give a push to start swinging. What two forces keep the swing moving back and forth?
A) Magnetism and friction
B) Gravity pulling down and a push giving it speed
C) Air pressure and electricity
D) Sound waves and heat
Gravity pulls the swing back to the middle, and the push adds energy to start the back-and-forth motion.
3. When a rider squeezes the brake levers on a bike, the wheels slow down. What causes the slowing?
A) Magnets inside the wheels
B) Friction between brake pads and wheel
C) Gravity pulling the wheels down
D) Air resistance on the rider's helmet
Brake pads press on the wheel and create friction, which slows and stops the bike.
4. A skydiver who closes their parachute mid-fall will MOST LIKELY do what?
A) Speed up because air resistance drops
B) Stop falling immediately
C) Stay at the same speed forever
D) Fly upward into the sky
With no parachute, air resistance is much smaller, so gravity pulls the skydiver faster.
Part B: Fill in the Blank
Write the correct answer on each line.
1. The force that pulls a swing back down toward the ground is gravity.
Gravity is the force that constantly pulls objects toward Earth, including a swinging child.
2. Air pushing back on a moving parachute is called air resistance.
Air resistance is the force of air pushing against moving objects, slowing them down.
3. Bike brakes work because of friction between the pads and the wheel.
Friction between the brake pads and the spinning wheel changes motion energy into heat and stops the bike.
4. On a swing, a bigger push gives the child more energy to swing higher.
A stronger push transfers more energy to the swing, allowing it to reach a higher point.
5. Without air resistance, a falling object would speed up as it falls.
Gravity keeps adding speed to a falling object, so without air pushing back, it speeds up the whole way down.