Numerical Problems Based on Force and Pressure for Class 8

Numerical Problems Based on Force and Pressure for Class 8

Here we are providing numerical problem for Class 8 Science (Physics). Solving numerical problems enhances understanding. In this article you will find numerical problems for ‘Force and Pressure’ with solutions. Students are suggested to solve the questions by themselves first. After completing all the questions review your answers with the help of given solutions.

Force and Pressure Numerical Problems

1. Problem: A book weighs 500 grams. Calculate the force exerted by the book due to gravity if the acceleration due to gravity is 9.8 m/s².

Solution:
Weight (Force) = Mass × Acceleration due to gravity
Weight = 0.5 kg × 9.8 m/s² = 4.9 N

So, the force exerted by the book is 4.9 Newtons.

2. Problem: A box has a mass of 10 kg. Calculate its weight on Earth and on the Moon. (Acceleration due to gravity on Earth is 9.8 m/s², and on the Moon, it is 1.6 m/s²)

Solution:
On Earth:
Weight = Mass × Acceleration due to gravity
Weight on Earth = 10 kg × 9.8 m/s² = 98 N

On the Moon:
Weight on the Moon = 10 kg × 1.6 m/s² = 16 N

So, the weight of the box on Earth is 98 N, and on the Moon, it is 16 N.

3. Problem: A force of 20 N is applied to a box with a mass of 5 kg. Calculate the acceleration of the box.

Solution:
Newton’s Second Law of Motion: \(F = ma\)
where F is the force applied, m is the mass, and a is the acceleration.

Rearrange the formula to find acceleration:
\(a = \frac{F}{m}\)

\(a = \frac{20 N}{5 kg} = 4 m/s²\)

So, the acceleration of the box is \(4 \, \text{m/s}^2\).

4. Problem: A force of 30 N is applied to an object with a mass of 5 kg. Calculate its acceleration.

Solution:
Using \(F = ma\):
\(a = \frac{F}{m} = \frac{30 \, \text{N}}{5 \, \text{kg}} = 6 \, \text{m/s}^2\)

The acceleration of the object is \(6 \, \text{m/s}^2\).

5. Problem: A car with a mass of 1000 kg is moving at a constant speed of 20 m/s. Calculate the force required to keep the car moving.

Solution:
Since the car is moving at a constant speed, the net force on it is zero (no acceleration). Therefore, the force required to keep it moving is also zero.

6. Problem: A girl exerts a force of 40 N to push a cart with a mass of 8 kg. Calculate the acceleration of the cart.

Solution:
Using \(F = ma\):
\(a = \frac{F}{m} = \frac{40 \, \text{N}}{8 \, \text{kg}} = 5 \, \text{m/s}^2\)

The acceleration of the cart is \(5 \, \text{m/s}^2\).

7. Problem: An object weighs 25 N on Earth. Calculate its weight on a planet where the acceleration due to gravity is \(3.5 \, \text{m/s}^2\).

Solution:
Using \(W = mg\):
\(W = 25 \, \text{N} \) on Earth
\(g = 3.5 \, \text{m/s}^2\) on the other planet
So, on the other planet: \(W = mg = 25 \, \text{N} \times 3.5 \, \text{m/s}^2 = 87.5 \, \text{N}\)

The weight on the other planet is \(87.5 \, \text{N}\).

8. Problem: A force of 15 N is applied to an object, causing it to accelerate at \(2 \, \text{m/s}^2\). Calculate the object’s mass.

Solution:
Using \(F = ma\):
\(m = \frac{F}{a} = \frac{15 \, \text{N}}{2 \, \text{m/s}^2} = 7.5 \, \text{kg}\)

The mass of the object is \(7.5 \, \text{kg}\).

9. Problem: A box weighing 60 N is pushed horizontally across the floor with a force of 30 N. Calculate the frictional force acting on the box.

Solution:
Frictional force = Applied force – Weight of the box
Frictional force = \(30 \, \text{N} – 60 \, \text{N} = -30 \, \text{N}\) (negative because it opposes motion)

The frictional force is \(-30 \, \text{N}\).

10. Problem: A bookshelf with a mass of 40 kg is placed on a horizontal floor. Calculate the normal force acting on it.

Solution:
The normal force on an object on a horizontal surface is equal in magnitude but opposite in direction to the weight of the object.
Normal force = Weight of the bookshelf
Normal force = \(40 \, \text{kg} \times 9.8 \, \text{m/s}^2 = 392 \, \text{N}\)

The normal force acting on the bookshelf is \(392 \, \text{N}\).

11. Problem: A 2 kg object is subjected to a force of 10 N. Calculate its acceleration.

Solution:
Using \(F = ma\):
\(a = \frac{F}{m} = \frac{10 \, \text{N}}{2 \, \text{kg}} = 5 \, \text{m/s}^2\)

The acceleration of the object is \(5 \, \text{m/s}^2\).

12. Problem: A force of 25 N is applied to an object with a mass of 5 kg. Calculate the acceleration, and also determine the direction of the acceleration.

Solution:
Using \(F = ma\):
\(a = \frac{F}{m} = \frac{25 \, \text{N}}{5 \, \text{kg}} = 5 \, \text{m/s}^2\)

The acceleration is \(5 \, \text{m/s}^2\) in the same direction as the applied force.

13. Problem: A child is pulling a wagon with a force of 15 N. If the wagon has a mass of 10 kg, calculate its acceleration.

Solution:
Using \(F = ma\):
\(a = \frac{F}{m} = \frac{15 \, \text{N}}{10 \, \text{kg}} = 1.5 \, \text{m/s}^2\)

The acceleration of the wagon is \(1.5 \, \text{m/s}^2\).

These additional numerical problems should further help you practice the concepts related to force and pressure in CBSE Class 8 Science.

Force and Pressure for Class 8

We use force all the time. We use force to open a door. We use force to pick up the school bag. We use force to brush our teeth. We use force to squeeze out toothpaste from a tube and so on.
Force is not an object which can be seen, force can be experienced or measured. We can experience the force of pull of earth on us and can measure it by a weight machine.
Now we are in position to define the force
“Force is a push or pull acting on an object”

Solving numerical problems in CBSE Class 8 not only helps you excel academically but also equips you with valuable skills and knowledge that can benefit you in various aspects of your education and future endeavors.

Benefits of Solving Numerical Problems in Class 8

1. Enhanced Understanding: Numerical problems require you to apply concepts and formulas, leading to a deeper understanding of the subject matter.
2. Application of Theoretical Knowledge: Numerical problems allow you to apply theoretical knowledge to real-world situations, making the learning experience more practical and relevant.
3. Improved Problem-Solving Skills: Regular practice with numerical problems hones your problem-solving skills, which are valuable not just in academics but also in daily life.
4. Concept Reinforcement: Solving numerical problems reinforces the concepts learned in class, helping you remember and apply them effectively.
5. Critical Thinking: Numerical problems often involve critical thinking and analysis, encouraging you to think creatively and find solutions to complex situations.
6. Preparation for Examinations: Regular practice with numerical problems prepares you for the types of questions that are commonly asked in examinations, boosting your exam readiness.
7. Increased Confidence: Successfully solving numerical problems boosts your confidence in your ability to handle challenging tasks.
8. Improved Time Management: Numerical problems often have time constraints, teaching you to manage your time efficiently and work under pressure.

[mathjax]