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# Forces and Weight ## Objectives * This spread should help you understand forces and how they are measured. * It explains what weight and gravitational field strength are. ## Forces A force is a push or pull, measured in newtons (N). Small forces can be measured using a spring balance (newtonm...

# Forces and Weight ## Objectives * This spread should help you understand forces and how they are measured. * It explains what weight and gravitational field strength are. ## Forces A force is a push or pull, measured in newtons (N). Small forces can be measured using a spring balance (newtonmeter). The greater the force, the more the spring is stretched, and the higher the reading on the scale. Here are some examples of forces: * Force to switch on a bathroom light: 10N * Force to open a drinks can: 20N * Force to lift a heavy suitcase: 200N * Force from a jet engine: 250,000N **Types of Forces:** * **Tension:** The force in a stretched material. * **Weight:** The downward pull of gravity. * **Friction:** The force that tries to stop one thing sliding past another. * **Air resistance:** Another type of friction. ## Gravitational Force If you hang something from a spring balance, you can measure a downward pull from the Earth. This pull is called a gravitational force. All masses attract each other. The larger the masses, the stronger the force. The closer the masses, the stronger the force. The force between everyday objects is usually too weak to measure, unless one of the objects has a large mass like the Earth. ## Weight and Gravitational Field Strength Weight is another name for the gravitational force from the Earth. It's measured in Newtons (N). On Earth, each kilogram (kg) of matter weighs 10N. The gravitational field strength of the Earth is 10 N/kg. This is represented by the variable *g*. If you know the mass of an object you can calculate its weight using the following formula: weight = mass x g (where *g* is 10 N/kg on Earth) For example, if a person has a mass of 50kg their weight is: weight = 50kg x 10 N/kg = 500N People often use the word "weight" when they really mean "mass". ## Questions **Question 1:** What do each of the above (forces) stand for? *(This would require the image/document to show the complete list of force examples, which is not provided in the OCR)* **Question 2:** Which of the above would you use to measure: a) Mass? b) Force? c) Weight? **Question 3:** *Diagram of a climber swinging on a rope*. Draw a simple version of the diagram. Show three forces acting on the climber and label them. **Question 4:** Calculate the weights of the following masses, assuming *g* is 10 N/kg: * 2kg * 4kg * 0.5kg