Inertia · F = ma · Action & Reaction
Tap a card to flip it. Each card stays open for 8 seconds, then flips back. You can open any card as many times as you like — but only one at a time.
Tap a term on the left, then tap its matching definition on the right. Correct matches turn green. (1 point each)
The puck is launched at the same speed every time — the only thing you change is the surface. Run each surface, watch how far the puck slides before friction stops it, then record the stopping distance.
Record the stopping distance for each surface. Completing all four = 4 points.
| Surface | Stopping Distance (m) |
|---|
Imagine riding in a car traveling 50 kilometers per hour. Your whole body is moving at that same speed. When the driver suddenly slams on the brakes, the car stops — but your body still wants to keep moving forward at 50 kilometers per hour. This tendency to keep moving is called inertia.
A seatbelt applies a backward force across your chest and hips. That unbalanced force is what actually stops your body, instead of the dashboard or windshield stopping it. Airbags work the same way, spreading the stopping force over a larger area and a longer time so the force on any one part of your body is smaller. Headrests stop your head from snapping backward when a car is hit from behind. Every safety feature in a car is really a tool for applying a controlled force to overcome the inertia of a passenger.
When a car stops suddenly, your body keeps moving forward because of .
Adjust the force and mass. Acceleration is calculated live, and the cart speeds up at that rate. You will use this simulator to collect data for the two investigations below.
| Force (N) | Mass (kg) | Acceleration (m/s²) |
|---|
| Force (N) | Mass (kg) | Acceleration (m/s²) |
|---|
A box is pushed to the right with 30 N while friction pushes left with 12 N.
Net force = 30 N − 12 N = 18 N to the right. Because the net force is not zero, the box accelerates in that direction.
Set the thrust, release the balloon, and a timer measures how long it takes to cross the string. Run each thrust setting and record the crossing time.
Record the crossing time for each thrust setting. Completing all five = 4 points.
| Thrust Setting | Time to Cross (s) |
|---|
A rocket carries fuel that burns inside its engines. The burning fuel creates hot gas that is forced out of the bottom of the rocket at tremendous speed. This downward push of gas is the action force.
According to Newton's third law, the escaping gas pushes back on the rocket with an equal force in the opposite direction. This upward reaction force is called thrust, and it is what lifts the rocket off the launch pad. A rocket does not need air to push against — it works even better in the vacuum of space, because there is no air resistance slowing it down. The same principle explains why a swimmer who pushes water backward glides forward, and why a balloon zips across a room when you let it go.
A rocket moves forward because the exhaust gases are pushed .
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