⚡ Force Calculator
Calculate force
How to Use This Calculator
Enter Mass
Input the mass of the object in kilograms (kg). For example, a 10 kg object would be entered as 10. Mass is the amount of matter in an object and remains constant regardless of location.
Enter Acceleration
Input the acceleration in meters per second squared (m/s²). For example, Earth's gravity is 9.81 m/s². Acceleration can be positive (speeding up) or negative (slowing down).
Click Calculate
Press the "Calculate Force" button to compute the force using Newton's Second Law. The result will be displayed in Newtons (N).
Review Results
See the calculated force in Newtons. The formula calculation will also be shown so you can verify the math step-by-step.
Formula
F = m × a
where F = force (N), m = mass (kg), a = acceleration (m/s²)
Example 1: Weight of an object on Earth
Given: m = 10 kg, a = 9.81 m/s² (gravity)
F = m × a = 10 × 9.81 = 98.1 N
This is the weight (gravitational force) of a 10 kg object on Earth.
Example 2: Force to accelerate a car
Given: m = 1500 kg, a = 2 m/s²
F = m × a = 1500 × 2 = 3,000 N
A force of 3,000 N is needed to accelerate a 1,500 kg car at 2 m/s².
Example 3: Braking force
Given: m = 800 kg, a = -5 m/s² (deceleration)
F = m × a = 800 × (-5) = -4,000 N
A braking force of 4,000 N (opposite direction) is needed to decelerate the vehicle.
About Force Calculator
The Force Calculator computes force using Newton's Second Law of Motion: F = ma, where F is force, m is mass, and a is acceleration. This fundamental physics equation describes the relationship between force, mass, and acceleration. Force is measured in Newtons (N), where 1 N = 1 kg⋅m/s².
When to Use This Calculator
- Physics Homework: Calculate force from mass and acceleration
- Engineering Design: Determine forces needed for mechanical systems
- Vehicle Analysis: Calculate engine force, braking force, or acceleration force
- Weight Calculations: Find weight (force of gravity) on different planets
- Sports Science: Analyze forces in athletics and training
- Exam Preparation: Practice Newton's Second Law problems
Why Use Our Calculator?
- ✅ Accurate Calculations: Precise physics calculations using Newton's Second Law
- ✅ Step-by-Step Display: Shows the formula calculation for verification
- ✅ Easy to Use: Simple interface for all skill levels
- ✅ Handles All Cases: Works for positive and negative acceleration
- ✅ Instant Results: Get answers immediately without manual calculations
- ✅ Completely Free: No registration or payment required
Understanding Force
Force is a push or pull that can change an object's motion. According to Newton's Second Law, the net force acting on an object equals the mass times the acceleration.
- Units: Force is measured in Newtons (N). 1 N = 1 kg⋅m/s²
- Weight: Weight is the force of gravity: W = mg, where g ≈ 9.81 m/s² on Earth
- Mass vs Weight: Mass is constant, but weight depends on gravity (mass × acceleration)
- Direction: Force is a vector quantity—it has both magnitude and direction
- Net Force: When multiple forces act, the net force determines acceleration
Real-World Applications
Car Acceleration: A 1,200 kg car accelerates at 3 m/s². Force needed: F = 1,200 × 3 = 3,600 N. This is the force the engine must produce.
Weight on Moon: A 70 kg person weighs 70 × 9.81 = 686.7 N on Earth, but only 70 × 1.62 = 113.4 N on the Moon (g_moon = 1.62 m/s²).
Braking: To stop a 800 kg vehicle from 20 m/s in 4 seconds (deceleration = -5 m/s²), braking force needed: F = 800 × (-5) = -4,000 N.
Tips for Using This Calculator
- Use consistent units: kilograms (kg) for mass, m/s² for acceleration, Newtons (N) for force
- Mass must be positive, but acceleration can be positive or negative
- For weight calculations, use g = 9.81 m/s² on Earth
- Remember: weight and mass are different—mass is constant, weight depends on gravity
- For multiple forces, calculate each separately and then find the net force
- Negative acceleration means deceleration (slowing down)
Frequently Asked Questions
What is Newton's Second Law?
Newton's Second Law states that F = ma: the net force acting on an object equals its mass times its acceleration. This is one of the fundamental laws of classical mechanics.
What is the difference between mass and weight?
Mass is the amount of matter in an object (measured in kg) and is constant. Weight is the force of gravity on that mass (measured in N) and varies with location. On Earth, weight = mass × 9.81.
What units are used for force?
Force is measured in Newtons (N) in the SI system. 1 N = 1 kg⋅m/s². In other systems, force might be measured in pounds-force (lbf) or dynes.
Can force be negative?
Yes! Force is a vector quantity with direction. A negative force typically indicates direction opposite to a chosen positive direction, or a decelerating force (like braking).
How do I calculate weight on different planets?
Use the same formula F = ma, but change the acceleration (g) to that planet's gravitational acceleration. For example, on the Moon, g = 1.62 m/s², so weight = mass × 1.62.
What if there are multiple forces acting on an object?
Calculate the net force (sum of all forces) first, then use F_net = ma. Forces in the same direction add; forces in opposite directions subtract.
Is this the same as calculating weight?
Weight is a specific type of force—the gravitational force. When a = g (9.81 m/s² on Earth), F = mg gives you weight. So yes, this calculator can calculate weight!