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Gravity
Gravity
• Earth’s gravity pulls objects toward the center of the Earth and gives them weight.
• Weight is a force measured in Newtons (N).
Newtons
• Newtons are named a@er Sir Isaac Newton.
• On Earth every kilogram of mass is pulled down by gravity with a force of 10 N.
Gravity
• Other planets also have gravity but the size of the gravity may be different from the Earth.
• Objects weigh more where the gravity is bigger.
Gravity
• Gravity is an invisible force. It holds you onto the Earth.
• It speeds you up when you cycle downhill • It pulls you back when you cycle uphill
Gravity
• It makes everything fall to the ground • It holds the Moon in its orbit around the Earth, and the Earth in orbit around the Sun.
• You cannot see it, but you can observe its effects
Gravity
• Gravity is a pulling force. It never pushes. • The pull is always in a straight line towards the center of the Earth.
Mass
• Like all objects you have mass. • Mass tells you how much material is in your body.
• Mass is measured in grams (g) or in kilograms (kg).
Weight
• Mass is o@en confused with weight. • Weight tells you how strong the force of gravity is pulling on your mass.
• Weight is a force and is measured in Newtons (N).
Mass & Weight
• What happens to your mass and weight on the moon?
• The mass of an object NEVER changes no maRer where you take it.
Mass & Weight
• If your mass on Earth was 50 kg, your mass on the moon would remain the same at 50kg. This is because you are sTll made of the same about of material.
• Your weight on the moon would be different, because the force of gravity on the moon is different.
Weight
• Given the force of gravity is one-‐sixth of that of the earth, your weight would be:
• 500 N divided by 6 = 83.3 N
• Explain what gravity is.
• Explain in your own words the difference between mass and weight.
• Jupiter has a gravity pull which is 2.5 Tmes greater than on Earth. Mr Stace’s mass is 80 kg. What is his mass and weight on the surface of Jupiter.