Newton's 1st Law
What is inertia?
An object’s tendency to resist changes in motion.
What three things are related in Newton’s 2nd Law?
Force, mass, and acceleration.
Write the formula for Newton’s 2nd Law.
F = m × a
What does Newton’s 3rd Law say?
For every action force, there is an equal and opposite reaction force.
What happened to make the balloon rocket move?
Air rushed out of the balloon.
Which has more inertia: a pencil or a bus?
The bus (more mass = more inertia).
If force increases and mass stays the same, what happens to acceleration?
Acceleration increases.
A 2 kg object accelerates at 3 m/s². What force is applied?
F = 2 × 3 = 6 N
Are action and reaction forces equal or different?
Equal in size.
What was the action force in the lab?
Air pushing backward out of the balloon.
Why does a book stay still on a desk?
Because no unbalanced force acts on it.
If mass increases and force stays the same, what happens to acceleration?
Acceleration decreases.
A 4 kg object is pushed with 20 N of force. What is its acceleration?
a = 20 ÷ 4 = 5 m/s²
Do action and reaction forces act on the same object?
No, they act on different objects.
What was the reaction force in the lab?
The rocket moving forward along the string.
Why do passengers move forward when a car suddenly stops?
Their bodies keep moving forward due to inertia.
Why is it harder to push a full shopping cart than an empty one?
More mass means less acceleration for the same force.
A 3 kg object accelerates at 5 m/s². What force is applied?
F = 3 × 5 = 15 N
How does walking demonstrate Newton’s 3rd Law?
You push the ground backward; the ground pushes you forward.
What happened when mass was added to the rocket?
It accelerated less and traveled a shorter distance.
Explain why an object in motion keeps moving unless an unbalanced force acts on it. Give a real-life example.
Objects naturally maintain their motion unless a force changes it; example: a soccer ball keeps rolling until friction stops it.
Two objects are pushed with the same force. One accelerates faster. Explain why.
The faster object has less mass.
A force of 30 N causes an object to accelerate at 6 m/s². What is the mass?
m = 30 ÷ 6 = 5 kg
Explain why a rocket moves forward even though gases are pushed backward.
The rocket pushes gases backward (action), and the gases push the rocket forward (reaction).
Explain how the balloon rocket demonstrates BOTH Newton’s 2nd and 3rd Laws using evidence from the lab.
3rd Law: Air pushed backward, rocket moved forward with equal and opposite forces.
2nd Law: Adding mass reduced acceleration when the same force (escaping air) acted on it.