How to Calculate Pendulum Force

In a vacuum, a pendulum will never stop swinging.
••• Hemera Technologies/ Images

When a pendulum moves away from its resting position, gravity forces it to swing back. This force is a function of the earth's constant acceleration due to gravity, the pendulum bob's mass and the angle between the pendulum and the vertical. Specifically, the force equals the mass times gravity times the sine of that angle - (F = mg sinθ). When the string is light, treat it as massless and ignore it in the pendulum force calculation. The string's length has no effect of the force on the pendulum, though it does affect how long the bob takes to swing.

    Find the sine (sin) of the angle between the string and the vertical. If you don't have a scientific calculator, use the online calculator (see first link Resources section). For example, with an angle of 20 degrees: sin(20) = 0.342.

    Multiply the result from Step 1 by the earth's gravitational acceleration, which is 9.81 meters per second squared: 0.342 x 9.81 m/s^2 = 3.36 m/s^2.

    Multiply the result from Step 2 by the bob's mass. For example, if the bob weighs 2 kilograms (kg), the calculation is 3.36 m/s^2 x 2 kg = 6.72. This is the force pushing the pendulum bob, measured in newtons.

Related Articles

Facts on Reentry into the Earth's Atmosphere
What Is the Purpose of the Pendulum?
How to Find the Magnitude When Force & Angle Is Given?
How to Solve Atwood Machine Problems
Laws of Pendulum Motion
History of the Pendulum
How to Calculate Triangle Dimensions
How to Make a Pulley for Children
Different Types of Pendulums
How to Calculate Overturning Moment
How to Calculate Kinetic Energy
How to Calculate Torsion Constant
How to Calculate the Mass of a Moving Object
List of Metals That Are Attracted to Magnets
How to Calculate a Change in Momentum
How to Convert Horsepower to Thrust
How to Calculate Contact Force
How to Calculate the Area of a Curved Surface
How to Calculate Load Force
Why Is a Pendulum Scientifically Important?

Dont Go!

We Have More Great Sciencing Articles!