A spring can be stretched by hanging masses on it. The larger the force, the greater the stretch.

# Forces 01

This KS3 Science quiz asks questions on forces. It doesn't matter if something is moving or stationary, there are always forces acting on it. The famous Scientist, Isaac Newton, realised this and came up with his three laws of motion. Forces are measured in newtons which have the symbol N. One of the most famous of Newton's laws is that if an object isn't moving, the forces acting on it are equal and opposite.

Imagine a book lying down on a shelf. The book puts a downward force on the shelf. The shelf must therefore be putting exactly the same force back on the book. Now if you add a whole lot more books to the shelf, if the shelf can't push back with the same force that the pile of books is putting on the shelf, it moves - in other words, it collapses! The force a book puts on a shelf is its weight. Weight is therefore measured in newtons. Unfortunately, in everyday life, you will hear most people referring to weight using kilograms. This is entirely incorrect, kilograms are a measure of mass. Weight is the force created by the attraction of gravity on the mass of an object. On Earth, a mass of 100g (0.1kg) has a weight of about 1N.

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1. Which of the following is NOT a touching force?
Magnets attract or repel at a distance, they do not need to touch the object they are acting on to have an effect
2. Which of the following is NOT a force?
Mass is measured in grams, kilograms etc
3. What is force measured in?
Forces can act in any direction. When drawing forces, you must always show in which direction they are acting
4. On Earth, 1kg weighs approximately 10N. What would be the weight of 500g?
500g = 0.5kg, 0.5kg weighs 0.5 x 10 = 5N
5. Which of the following statements about unbalanced forces is NOT true?
Unbalanced forces will ALWAYS create movement
6. What is weight measured in?
Weight is a force and therefore should be measured in newtons
7. A spring can be stretched by hanging masses on it. Which of the following is true?
According to Newton's third law of motion, if the mass puts a force on the spring, the spring must be putting a force on the mass
8. Friction .......
Friction is a force
9. Which of the following statements about balanced forces is NOT true?
This is Newton's third law of motion
10. On Jupiter, 1kg weighs approximately 25 newtons. What would be the weight of 100g?
100g = 0.1kg, 0.1kg weighs 0.1 x 25 = 2.5N. The weight of an object depends on the force of gravity that is acting on it. The Moon has a gravity of about one sixth of that of the Earth, so 1kg would weigh a lot less than on the Earth, whilst on the planet Jupiter, it would weigh a lot more as the force of gravity there is larger

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