Forces

A force is a Push Or a Pull

What forces do you know?

Magnets The world is full of pushes and pulls. Pushes and pulls are forces in action. A magnet is special; it can push or pull something without touching it. Magnets have centres of push and pull called the poles of the magnet. Poles that are the same repel (push) each other. Poles that are different attract (pull) each other. Magnets also attract some metals. http://www.bbc.co.uk/schools/revisewise/science/physical/12_act.shtml

Springs Springs exert forces, too. They push back if you squeeze them; and pull back if you stretch them. When you let them go, they go back to their original shape.

Gravity Gravity is a force which acts on every object – The larger the object the greater the gravity. The sun is the largest thing in the universe. It keep our planet in its orbit.

The Earth is a huge object too. Its gravity pulls things towards it.

Friction Rub your hands across the table. What stops them moving? What happens when you rub Your hands together. Friction is a force that slows movement. It can slow your movement down the park slide (solid against solid), or swimming through the water (solid against liquid) or dropping with a parachute (solid against gas). Friction takes place between the tiny bumps and pits in solid materials. So even materials that look and feel very smooth can be slowed by friction.

Where is friction important?

Friction Experiment Which material has the most friction? A car was rolled down a ramp. The children measured how far it travelled. They then tested different materials like carpet and paper. How could they make it a fair test?

Results

Air Resistance Why does this happen? If you were to drop two objects at the same time like a hammer and a feather and a ball which would you expect to hit the floor first? Why does this happen?

Air resistance is very useful for slowing things down through the air

Now youv’e learnt about Air resistance, friction and gravity try this http://www.bbc.co.uk/schools/revisewise/science/physical/12b_act.shtm l Force direction/balaned/unbalanced forces http://www.bbc.co.uk/schools/revisewise/science/physical/13_act.shtml http://www.channel4.com/weblogic/essentials/science/physical/quiz.jsp?unit=Forces+in+action&unitShortName=forcesaction&rand=1069676415290

Label the forces in the following activity

Forces are measured in Newtons after the scientest Sir Isaac Newton Measuring Forces Forces are measured in Newtons after the scientest Sir Isaac Newton http://www.learnpremium.co.uk/Whiteboardactiv/Science/Keystage2/Year4/Friction/Whiteboard/default.asp