Worksheets › Class 9 › How Forces Affect Motion
Class 9 How Forces Affect Motion worksheet
CBSE Science. Inertia, F = ma, momentum and its conservation. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
A force acting on a mass of 9 kg gives it an acceleration of 6 m/s². The force is:
- 1.5 N
- 15 N
- 108 N
- 54 N
Answer
(d) 54 N
F = ma = 9 × 6
- 2.
A force of 180 N acts on a body of mass 20 kg. Its acceleration is:
- 9 m/s²
- 3600 m/s²
- 20 m/s²
- 11 m/s²
Answer
(a) 9 m/s²
a = F ÷ m = 180 ÷ 20
- 3.
The momentum of a 32 kg object moving at 2 m/s is:
- 16 kg m/s
- 34 kg m/s
- 65 kg m/s
- 64 kg m/s
Answer
(d) 64 kg m/s
p = mv = 32 × 2
Section B · short answer
- 4.
A car of mass 1,600 kg speeds up from 5 m/s to 13 m/s in 9 s. Find the force on it. (Give the answer to 2 decimal places where needed.)
Answer
1,422.22 N
F = m(v − u) ÷ t = 1600 × 8 ÷ 9
- 5.
A trolley of mass 2 kg moving at 20 m/s hits a 7 kg trolley at rest, and they move off together. Find their common velocity. (Give the answer to 2 decimal places where needed.)
Answer
4.44 m/s
momentum is conserved: 2 × 20 = (2 + 7) × v
Section C · long answer
- 6.
A fielder catches a cricket ball of mass 167 g moving at 18 m/s, stopping it in 0.4 s. Find the average force on the fielder's hands. (Give the answer to 2 decimal places where needed.)
Answer
7.52 N
F = m v ÷ t = 0.167 × 18 ÷ 0.4
Fresh sheets for your child
In the app, every How Forces Affect Motion sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
Coming soon for Android and iPhone.