This Science quiz is called 'Forces 1' and it has been written by teachers to help you if you are studying the subject at middle school. Playing educational quizzes is a fabulous way to learn if you are in the 6th, 7th or 8th grade - aged 11 to 14.
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There are many types of force, such as thrust, magnetism and gravity. The famous scientist Galileo wanted to know whether gravity exerted the same force on all objects whatever their mass (the amount of matter an object contains). He dropped a cannonball and a small stone off the top of the tower of Pisa - and both hit the ground at the same time, showing that gravity always has the same force on all objects. Feathers only fall more slowly because of friction with the air. On the Moon a feather and a hammer fall at the same rate. Many people don't believe this until they try a similar experiment themselves.
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Parachutes work by maximizing air resistance
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Rough surfaces give much better 'grip' than smooth ones
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Balanced forces are equal forces acting in opposite directions
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Magnets can attract (pull) and repel (push) objects
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Brakes and tires are designed to have high friction, so as to slow the bike down and give it grip
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Without the 'upthrust' of the table, gravity would pull the bowl down (through the table)! When you look at a stationary object, such as the bowl, you can't see the balanced forces at work - but they are still there
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You can rub your hands together to warm them up. The friction causes heat
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Compressing is the opposite of stretching
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A thick, stiff spring takes more force to stretch, allowing the Newtonmeter to measure greater forces. Newtonmeters designed for small forces will have thin, flexible springs
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Forces can change the shape of a material, but not what it is!
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