Year 9 Science · Unit 4 · Lesson 16
Apply Worksheet
Learning Goals
Match each term to its definition
Draw a line connecting each Newton's Law on the left to the correct description AND example on the right. Or write the matching letter next to each law.
| Newton's Law | Your answer | Description and example |
|---|---|---|
| First Law (Inertia) | A. The harder you kick a soccer ball, the faster it accelerates — but a heavier ball accelerates less for the same kick. (F = ma) | |
| Second Law (F = ma) | B. A seatbelt is needed when a car stops suddenly because passengers continue moving forward at the car's original speed unless a force acts on them. |
Road safety scenario
A 1200 kg car is travelling at 100 km/h (27.8 m/s) when the driver applies the brakes. The car decelerates uniformly and comes to a complete stop in 4 seconds. Use this information to answer the questions below.
(a) Calculate the deceleration of the car. Use the formula: a = Δv ÷ Δt, where Δv = change in velocity and Δt = time taken. Show your working.
(b) Calculate the braking force applied to the car. Use F = ma with the mass of the car and the deceleration you calculated in part (a). Show your working.
(c) Explain, in terms of Newton's First Law (inertia), why passengers who are not wearing seatbelts continue moving forward when the car brakes. What role does the seatbelt play?
Wrap Up
In one sentence, what was the main idea of this lesson?