Force & Motion
What is the relationship between mass and the force needed to change an object’s motion?
Greater mass requires more force to change motion.
A book resting on a table. Balanced or unbalanced?
Balanced
What does Newton’s First Law say about objects at rest?
They stay at rest unless acted on by an unbalanced force.
What is the formula for Newton’s Second Law?
F = ma
What does Newton’s Third Law state?
For every action, there is an equal and opposite reaction.
A 3 kg object accelerates at 20 m/s². What is the net force acting on it?
60 N (using F = ma)
A soccer ball being kicked across a field. Balanced or unbalanced?
Unbalanced
Why does a passenger lurch forward when a car suddenly stops?
Inertia keeps the passenger moving forward.
If you apply the same force to a small and large object, which accelerates more?
The smaller object accelerates more.
A swimmer pushes water backward. What happens next?
The swimmer moves forward.
A car accelerates from 10 m/s to 35 m/s in 20 seconds. What is its acceleration?
1.25 m/s²
A tug-of-war where both teams pull with equal force. Balanced or unbalanced?
Balanced
Describe what happens to a ball rolling on a frictionless surface.
It continues moving at constant speed indefinitely.
A 10 kg object accelerates at 3 m/s². What is the force?
30 N
A person jumps off a boat. What happens to the boat?
It moves in the opposite direction.
Describe what happens to a wagon’s motion when two people begin pushing it from behind.
Net force increases, causing the wagon to accelerate forward.
A person jumps off a docked boat, causing the boat to drift backward. Balanced or unbalanced?
Unbalanced
Explain why seatbelts are important in a moving vehicle.
They counteract inertia during sudden stops.
How does doubling the force affect acceleration (if mass stays the same)?
Acceleration doubles.
Two skaters are facing each other and push off each other. Compare the forces they experience.
Each skater experiences a force that is equal in magnitude but opposite in direction. The forces are the same strength, but they act on different skaters and push them away from each other.
Predict the motion of a wagon if one person pushes from the front and another from the back with equal force.
Forces are balanced; net force is zero, so the wagon doesn’t accelerate.
A skateboarder coasting to a stop due to friction. Balanced or unbalanced?
Unbalanced
A hockey puck slides across ice and slows down. What force is acting on it?
Friction is the unbalanced force slowing it down.
A wagon’s mass increases but force stays the same. What happens to acceleration?
Acceleration decreases.
Explain how a rocket launches using Newton’s Third Law.
Exhaust gases push down; rocket is pushed upward in reaction.