Evaluating ExperimentsEvaluating Experiments

D. Crowley, 2007D. Crowley, 2007

Evaluating ExperimentsEvaluating Experiments

• To be able to evaluate experiments, and know the difference between mass and weight

• To be able to evaluate experiments, and know the difference between mass and weight

Wednesday, April 19, 2023

Results - Newton MeterResults - Newton Meter

• Last lesson you collected results of how a spring changed length, when different masses were added to it

• 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)

0 0

100 1

200 2

300 3

Graph & ResultsGraph & 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 WeightMass 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 WeightMass 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 WeightMass versus WeightAstronaut = mass of 80kg anywhere in Universe, but…Weight varies, depending upon the pull of gravity

EarthAstronaut Mass = 80kgEarth Gravity = 10N/kgWeight = 80 x 10 = 800N

MoonAstronaut Mass = 80kgMoon Gravity = 1.6N/kgWeight = 80 x 1.6 = 128N

ExamplesExamples

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

AnswersAnswersSee 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 10Weight = 1000N

4) My mass is 100kg. The pull of gravity on the Moon is 1.6N/kg. what is my weight?

Weight = 100 x 1.6Weight = 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 10Weight = 1000N

4) My mass is 100kg. The pull of gravity on the Moon is 1.6N/kg. what is my weight?

Weight = 100 x 1.6Weight = 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

PlanetsPlanetsUse 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)…

Planet Gravitation pull (N/kg)

Weight of 500kg mass (N)

Mercury 4

Venus 9

Earth 10

Mars 4

Jupiter 26

Saturn 11

Uranus 11

Neptune 12

Pluto 4

PlanetsPlanetsUse 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)…

Planet Gravitation pull (N/kg)

Weight of 500kg mass (N)

Mercury 4 2000

Venus 9 4500

Earth 10 5000

Mars 4 2000

Jupiter 26 13000

Saturn 11 5500

Uranus 11 5500

Neptune 12 6000

Pluto 4 2000

So you’re mass is always the same, but you’ll weigh loads more on Jupiter