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Learn the difference between mass and weight, explore gravitational forces on planets, and understand how mass and weight vary in different planetary environments. Practical activities and discussions enhance understanding of gravity's impact on objects. Interactive sessions engage students in practical applications.
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Gravity and Weight 20 October 2019 Objectives: To describe the difference between mass and weight on the surface of planets. To describe the gravitational forces between planets.
Starter (5 mins) • Place a labelled 1 kg metal mass in front of the students and ask them to describe exactly what it is and the properties it has. • Key points: particles (atoms), physical properties and the forces acting on the block
What is gravity? Satellite’s gravity Earth’s gravity Gravityis an attractive force that acts between all objects that have mass. The size of the force depends on the masses of the objects. All objects produce a gravitational force. This is very large for huge masses such as planets. When you jump, the gravitational force of the Earth pulls you down. Your gravitational force also pulls the Earth towards you, but you don’t notice it because the Earth is too heavy to be visibly affected by your gravity.
What are mass and weight? Massis the amount of matter in an object and is measured in kilograms. Mass is not a force. An object, such as this satellite, has the same mass at any point in the Universe. Weightis a force and is caused by the pull of gravity acting on a mass. Weight is measured in newtons and has both magnitude and direction. An object’s weight changes depending on where it is in the Universe.
Mass and weight on the Moon The force of gravity on the Moon is only one-sixth of that on Earth because the Moon has a much smaller mass. Any object on the Moon weighs one-sixth of the amount it would weigh on Earth. Astronauts can jump up 20 feet on the Moon due to there being such a low gravitational force. However, the astronaut still has the same mass – they just weigh less because gravity is weaker.
Sheet • Can complete worksheet questions to check progress
Practical • Pupils can measure their mass and then calculate their weight on each planet
Practical • My mass is ………… kg
Plenary (10 mins) • Show the students the behaviour of ’toys in space‘ and have them compare their behaviour to those on Earth using the knowledge gained this lesson. • www.nasa.gov/audience/foreducators/microgravity/home/toys-in-space.html