Example 1 · level 1
A force of 36 N gives a trolley an acceleration of 3 m/s². What is its mass (in kg)?
Show solution
- m = 36 ÷ 3 = 12 kg.
Answer: 12 kg
CLASS 9 SCIENCE · FORCE AND LAWS OF MOTION
Newton's second law (F = ma)
Net force = mass × acceleration. 1 N is the force that gives a 1 kg mass an acceleration of 1 m/s².
Loading practice…
Worked examples
Example 2 · level 2
What net force (in N) is needed to give a 460 kg object an acceleration of 2 m/s²?
Show solution
- F = 460 × 2 = 920 N.
Answer: 920 N
Example 3 · level 3
A vehicle of mass 1,470 kg speeds up from 5 m/s to 11 m/s in 2 s. Find the net force on it (in N).
Show solution
- a = 6 ÷ 2 = 3 m/s².
- F = 1,470 × 3 = 4,410 N.
Answer: 4,410 N