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Understand different types of forces - friction, static, sliding, rolling, and fluid friction. Learn how to measure force and the impact of friction on motion.
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Forces Types of forces and friction
Force • A force is a push or a pull that acts on an object • A force can cause a resting object to move or it can accelerate a moving object by changing the object’s speed or direction • Example wind
Measuring Force • The unit of force is a newton • A newton causes one kilogram of mass to accelerate at a rate of 1 meter per second, each second • 1N = 1 kg*m/s2 • Named after Sir Isaac Newton (much different than fig newtons)
Combining Forces • 1. Adding Forces + = • Subtracting Forces = • Equal and opposite forces = 0
Friction • Friction is a force that opposes the motion of objects that touch as they move past each other • Without friction walking would be impossible, cars would slide around helplessly
Static Friction • Static Friction is the friction force that acts on objects that are not moving • Example you are trying to push a potted plant but can not move it, static friction is working against you • Each time you step you experience static friction between the ground and your shoe
Sliding Friction • Sliding friction is a force that opposes the direction of motion of an object as it slides over a surface • It is less than static friction • As the flower pot is moving there is less friction so it takes less force to move it
Rolling Friction • The friction force that acts on rolling objects • It is about 100 to 1000 times less than static or sliding friction • Example ball bearings used to reduce friction in machines
Fluid Friction • The forces that opposes the motion of an object through a fluid • You would feel this friction when you are stirring cake batter • Fluid friction increases as the speed of the object increases
Fluid Friction cont. • Fluid friction acting on an object through the air is known as air resistance • Bicyclists and speed skaters will wear slick racing suits to reduce air resistance