Force and Acceleration MCQs Quiz | Class 9
This quiz covers Class IX Science (Code 086), Unit III: Motion, Force and Work. It focuses on the topic of Force and Acceleration, including the formula F=ma, simple numerical problems, and the unit Newton. Test your understanding, check your score, and download the answer key PDF for revision.
Overview of Force and Acceleration
In Class 9 Science, Unit III covers the fundamental concepts of Force and Laws of Motion. Newton’s Second Law of Motion provides the quantitative definition of force. It states that the rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of force. This leads to the famous equation:
F = m x a
Where F is the force applied, m is the mass of the body, and a is the acceleration produced.
Key Concepts and Units
- SI Unit of Force: The Newton (N). One Newton is the force required to accelerate a mass of 1 kg by 1 meter per second squared.
- Acceleration: It is directly proportional to the force applied and inversely proportional to the mass of the object (a = F/m).
- Vector Quantity: Force has both magnitude and direction.
Quick Formulas for Numericals
| Quantity | Formula / Value | SI Unit |
|---|---|---|
| Force (F) | m x a | Newton (N) or kg m/s/s |
| Mass (m) | F / a | Kilogram (kg) |
| Acceleration (a) | F / m or (v – u) / t | m/s/s |
Solving Simple Numericals
To solve problems based on F = ma:
- Identify the given values (mass, initial velocity, final velocity, time).
- Calculate acceleration first if not given directly, using equations of motion like a = (v – u) / t.
- Substitute the value of ‘m’ and ‘a’ into F = ma to find the force.
Extra Practice Questions
- A force of 5 N gives a mass m1 an acceleration of 10 m/s/s and mass m2 an acceleration of 20 m/s/s. What acceleration would it give if both masses were tied together?
- Calculate the force required to impart a velocity of 30 m/s in 10 seconds to a car standing at rest. The mass of the car is 1500 kg.
- Which would require a greater force: accelerating a 2 kg mass at 5 m/s/s or a 4 kg mass at 2 m/s/s?
- A truck starts from rest and rolls down a hill with a constant acceleration. It travels a distance of 400 m in 20 s. Find its acceleration and the force acting on it if its mass is 7 tonnes.
- If the engine of a car provides a constant force, how does the acceleration change if the mass of the car is doubled (e.g., by adding a heavy load)?
Content created and reviewed by the CBSE Quiz Editorial Team based on the latest NCERT textbooks and CBSE syllabus. Our goal is to help students practice concepts clearly, confidently, and exam-ready through well-structured MCQs and revision content.