Forces A force is a push or a

Forces A force is a push or a pull that causes changes in motion. Start things moving Stop things moving Speeds things up Slows things down Makes them change direction Change an objects shape Nothing changes position, speed, or direction unless a force acts on it.

Friction is a force that works against motion. It is greater between rough surfaces. There is less friction on smooth surfaces. It can make heat when two objects are rub against each other.

Gravity is a force which pulls objects together. The bigger the object the larger the force of gravity. Our planet's gravity pulls everything towards the center of the Earth. It causes objects to speed up as they fall. Gravitational force is the pull of all objects in the universe on one another.

Outer space / http: //www. bbc. co. uk/bitesize/ks 3/science/energy_e lectricity_forces/revision/3 The moon has less mass than the Earth, so the moon pulls objects toward its center with less force. The mass of an object stays the same wherever it is, but its weight can change. Weight is the measurement of gravitational force acting on an object. .

Magnetic Force If something is magnetic it attracts iron objects. The force produced by a magnet is a magnetic force. They have two ends called poles. If allowed to float freely one end will point toward the North Pole and the other end toward the South Pole. If two of the same types of ends are held near each other, they will push away from each other. Opposite ends pull/stick together.

When two or more forces acting but cancel each other, you have balanced forces. This means there is no change in movement. When forces in one direction are stronger than another, you have unbalanced forces. This means the object may start to move, slow down, stop, or change directions.

The net force is the combination of all the forces action on an object. If it is a balanced force the net force is zero. If it is an unbalanced force the net force can be positive or negative.

Buoyant force is the upward force from water on an object.

Work-using a force to move an object a distance. Work = Force x Distance Simple machines can make work easier by reducing the amount of force people need to use to do the work.

A lever is a bar that makes it easier to move things. It has a fulcrum which usually changes the amount and/or direction of the force -Pry bar, teeter totter, bottle opener

A pulley is a wheel with a groove for a rope. It changes the direction of the force. -Flag pole, elevator, sails, crane, blinds

An inclined plane is a ramp that allows you to use less force over a distance. -Wheelchair ramp, playground slides, loading dock ramps

A wedge is used to push materials apart and sometimes cuts things. -Ax, doorstop, chisel, plow, scissors

The wheel and axle move things by rolling them and reducing friction. -Car, shopping cart, wheel barrow, bicycle

A screw is an inclined plane wrapped around a shaft. It turns rotation into lengthwise motion. -Screw, bolt, jar lid, grain auger