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CENTRIFUGAL FORCE - DIY kit for Students

Updated: May 1

CENTRIFUGAL FORCE is an inertial force which tends to pull an object out ward when it is in orbit or is rotating around a center.As a car makes a turn, the force of friction acting upon the turned wheels of the car provides centripetal force required for circular motion. As a bucket of water is tied to a string and spun in a circle, the tension force acting upon the bucket provides the centripetal force required for circular motion.

Centrifugal force is ubiquitous in our daily lives. We experience it when we round a corner in a car or when an airplane banks into a turn. We see it in the spin cycle of a washing machine or when children ride on a merry-go- round. One day it may even provide artificial gravity for space ships and space stations.

Centrifugal force is defined as an apparent force. In other words, when twirling a mass on a string,the string exerts an inward centripetal force on the mass, while mass appears to

exert an outward force on the string.

This apparent outward force is described by Newton’s Laws of Motion.Newton’s First Law stat s that“Abodyat rest will remain at rest,and a body in motion will remain in motion unless it is acted upon by an external force.”If amassive body is moving through space in a straight line,its inertia will cause it to continue in a straight line unless an outside force causes it to speed up,slowd own or change direction. In order for it to follow a circular path with out changing speed, a continuo us centripetal

force must be continuously applied at aright angle to its path.The radius of this circle is equal to the mass m times the square of the velocity v divided by the centripetal force F, or r = mv2/F. The force can be calculated by simply rearranging the equation, F= mv2/r.




Plastic bucket


3 V DC Motor

Screw T Shape Attachment

Battery Snap


Cable Tie

Hypothesis: What will happen to the water in the bucket when the bucket is spun faster? Slower?


The water will spill out of the bucket when the gravitational force of the water exceeds the centripetal force exerted on the water when it is upside down.


Centripetal force exerted on a spinning object like our bucket of water also leads to an equal and opposite centrifugal force, an apparent force that draws a rotating object away from the center of rotation (thus holding the water in the bottom of the bucket a s it passes overhead). Centrifugal force is a consequence of inertia—the tendency of a moving object to want to continue moving in a straight line. As we fling our bucket of water in an arc over our head, the water wants to continue traveling in a straight line, but our string constantly redirects the water so it travels in an arc instead! Water’s inertiaresists this redirection, leading to the apparent force that “pulls” the water into the bottom of the bucket. It’s a great example of Newton’s third law: The string pulls on the water to change its direction from a straight line to an arc (centripetal force),and the water’s inertia pulls back (centrifugal force)!

Here’s an analogous situation: Imagine you’r eriding as a passenger in your dad’s car. He makes a really sharp turn, and as a result, you feel like you’re being thrown against the inside of the car door. What’s really happening is that your body wants to continue moving forward, but the turning car pulls your body in a new direction. Your body’s in tertiaresists this pull, because like all objects,it wants to continue traveling in a straight line.


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