Evaluating Experiments D. Crowley, 2007

Evaluating Experiments To be able to evaluate experiments, and know the difference between mass and weight Monday, September 14, 2015

Results - Newton Meter Last lesson you collected results of how a spring changed length, when different masses were added to it Mass (g)Weight (N)Length of spring (cm)

Graph & Results Now you have your results, you need to produce a line graph - think about what goes on the bottom of the graph (what did you change) Produce a line of best fit, add a title and units to your graph Were there any anomalies? Why do you think this is? How accurate / reliable were your results? Then write up your results - what did you find? Was the experiment a success - could you improve it? Now you have your results, you need to produce a line graph - think about what goes on the bottom of the graph (what did you change) Produce a line of best fit, add a title and units to your graph Were there any anomalies? Why do you think this is? How accurate / reliable were your results? Then write up your results - what did you find? Was the experiment a success - could you improve it?

Mass versus Weight Be careful - mass and weight are two very different things Mass is the amount of stuff there is (in kg) Weight is caused by the pull of gravity (in N/kg) - this will be different if you are own the Earth / Moon / in a black hole! Be careful - mass and weight are two very different things Mass is the amount of stuff there is (in kg) Weight is caused by the pull of gravity (in N/kg) - this will be different if you are own the Earth / Moon / in a black hole!

Mass versus Weight For example - take a person who has a mass of 80kg If they are on the Earth, on the Moon, in fact anywhere in the Universe, their mass is always 80kg But their weight varies - weight is the mass x the force of gravity This force of gravity can vary - on Earth it is 10N/kg; on the Moon just 1.6N/kg For example - take a person who has a mass of 80kg If they are on the Earth, on the Moon, in fact anywhere in the Universe, their mass is always 80kg But their weight varies - weight is the mass x the force of gravity This force of gravity can vary - on Earth it is 10N/kg; on the Moon just 1.6N/kg

Mass versus Weight Astronaut = mass of 80kg anywhere in Universe, but… Weight varies, depending upon the pull of gravity Earth Astronaut Mass = 80kg Earth Gravity = 10N/kg Weight = 80 x 10 = 800N Moon Astronaut Mass = 80kg Moon Gravity = 1.6N/kg Weight = 80 x 1.6 = 128N

Examples See if you can answer the following questions on mass and weight… 1)My mass is 60kg on Earth. What is my mass on the moon? 2)If my mass is 60kg, what is it on the sun? 3)My mass is 100kg. The pull of gravity on Earth is 10N/kg. What is my weight? 4)My mass is 100kg. The pull of gravity on the Moon is 1.6N/kg. what is my weight? 5)Does weight change throughout the universe? See if you can answer the following questions on mass and weight… 1)My mass is 60kg on Earth. What is my mass on the moon? 2)If my mass is 60kg, what is it on the sun? 3)My mass is 100kg. The pull of gravity on Earth is 10N/kg. What is my weight? 4)My mass is 100kg. The pull of gravity on the Moon is 1.6N/kg. what is my weight? 5)Does weight change throughout the universe? Remember: - Weight = mass x pull of gravity

Answers See if you can answer the following questions on mass and weight… 1)My mass is 60kg on Earth. What is my mass on the moon? Mass is the same anywhere! It will be 60kg on the moon too 2)If my mass is 60kg, what is it on the sun? Mass is the same anywhere! It will be 60kg on the sun too 3)My mass is 100kg. The pull of gravity on Earth is 10N/kg. What is my weight? Weight = 100 x 10 Weight = 1000N 4)My mass is 100kg. The pull of gravity on the Moon is 1.6N/kg. what is my weight? Weight = 100 x 1.6 Weight = 160N 5)Does weight change throughout the universe? Yes! Weight depends on the pull of gravity. So if you’re on a massive planet you’ll weigh a lot more than on a small rock See if you can answer the following questions on mass and weight… 1)My mass is 60kg on Earth. What is my mass on the moon? Mass is the same anywhere! It will be 60kg on the moon too 2)If my mass is 60kg, what is it on the sun? Mass is the same anywhere! It will be 60kg on the sun too 3)My mass is 100kg. The pull of gravity on Earth is 10N/kg. What is my weight? Weight = 100 x 10 Weight = 1000N 4)My mass is 100kg. The pull of gravity on the Moon is 1.6N/kg. what is my weight? Weight = 100 x 1.6 Weight = 160N 5)Does weight change throughout the universe? Yes! Weight depends on the pull of gravity. So if you’re on a massive planet you’ll weigh a lot more than on a small rock Remember: - Weight = mass x pull of gravity

Planets Use the data below to work out how much a 500kg mass weighs on the planets in our solar system (copy this table into your books)… PlanetGravitation pull (N/kg) Weight of 500kg mass (N) Mercury4 Venus9 Earth10 Mars4 Jupiter26 Saturn11 Uranus11 Neptune12 Pluto4

Planets Use the data below to work out how much a 500kg mass weighs on the planets in our solar system (copy this table into your books)… PlanetGravitation pull (N/kg) Weight of 500kg mass (N) Mercury42000 Venus94500 Earth Mars42000 Jupiter Saturn Uranus Neptune Pluto42000 So you’re mass is always the same, but you’ll weigh loads more on Jupiter