Forces

Whenever planes hurtle overhead or cars screech to t halt, forces are working hard behind the scences. One a large scale, gravitational forces span the Universe, causing stars to cluster into galaxies and keeping plants whirling in orbit around the sun. At the other end of the scale, atoms cause forces like sticking and friction.

What is a force?

                A force is a push or pull that makes something happen, when you kick a ball, your foot supplies the force that makes the ball fly into the air. forces are usually invisible. Gravity is the invisible force that pins us to the ground, while magnetism is another hidden forces that makes a compass spin. simple forces can change an object's shape, alter it's direction, or change its speed.

Balanced Forces

                 It two equal forces act in opposite direction, they cancel each other out and there's no movement or change of any kind. Architects design building so that the download pul of gravity is balanced by upward forces inside the building.

Simple Machines 

               Levers, wheels, pulleys, and gears all magnify forces and make jobs easier to do. these forces magnifiers are called simple machines. If you sit on a see-saw, you can lift someone heavier by moving further from the balacing point. the see-saw works as a lever and muliplies your lifting forces.

Velocity and Acceleration

                  An object's speed in a certain direction is its velocity. If it speeds up or changes diection. its velocity changes. A change in velocity is called an acceleration. Force is needed to acceleration an object.

Increasing Velocity

When a car sppeds up. its engine produces more force to make the vehicle accelerate.

Changing direction

As a car turns, it accelerates, speed even if it keeps the same speed, since the change in direction changes the car's velocity.

Decreasing velocity 

When the driver brakes, force is applied to the wheels, slowing the car. this is called deceleration, or negative acceleration.

Relative Velocity

The difference in speed between two moving objects is called their relative velocity. Because velocity is speed in a particular direction, you have to take account of the direction in which the object are moving when you calculate their relative velocity.

What's Faster

Machines with powerful engines, such as rockets, usually go fast because their engines produce enormous forces to push them forwards at high speed. object can travel even faster in space as they move away from the downward pull of earth's gravity.