mass and weight

1. Weight and MASS

2. What we want to achieve....
• Be able to recall the difference between
mass and weight
• Be able to calculate you weight on other
planets
• Be able to describe why the value of
gravity is different on different planets

3. Brainstorm, what do we already know
about gravity?
Gravity

4. Newton is famous for his theory of gravity
He actually worked out how the mathematics or the ‘rules or gravity’
The rules of Gravity affect everything that has mass so that means
You, books, calculators, the planets, stars and teachers.
All masses are attracted to each other
The force of gravity depends on the distance between the two masses and the
Size (magnitude) of the two masses
FORCE is measured in NEWTONS (N)
He is famous for the apple story
Although this probably never happened

5. Gravity pull all objects down at the same rate
Air resistance will slow some object but there is no air on the moon so...

6. MASS and WEIGHT are NOT the same thing!!!!!!!!!!
120kg 120kg x 10 = 1200 N
x Gravity
Mass is the same wherever you are as it is the amount of stuff (particles) that are in you
Weight is your mass multiplied by the gravitational pull of the planet you are on
On Earth your weight is roughly 10x your mass
Your weight is a force and is measured in Newtons

7. On the moon the gravitational force is 6 time less than on Earth
120kg 120kg x 1.6 = 200N
x Gravity
This is because the moon has 1/6 less mass than the Earth it has 1/6 less gravitational pull
The man has lost weight by going to the moon but what about his mass?

8. If you know your weight in KG you can use that, otherwise use 50KG as your mass
Place Weight of 1Kg Calculation Your weight (N)
Earth 10N
Mars 4N
Jupiter 23N
Pluto 3N
Uranus 11N
Venus 9N
Neptune 10.6N
On the moon 0.1N
In deep space 0N
Copy into your book the table above and calculate your weight
Remember weight = mass x gravity
Conclusion-
Where in the solar system would you weigh the most? How much would you weigh?
Where in the solar system would you weigh the least? How much would you weigh?
Trick Question
What would your mass be on the moon
What would your mass be on Pluto

9. Video review
Watch the video and answer these questions
1)What objects equal roughly 1 Newton?
2)What is 1 Newton in Kgs?
3)What is the force of gravity measured in?
4)What is weight measured in?
5)How much does your mass change when you are on the moon?
6)Why do you weigh less on the moon? (refer to the mass of the moon)

10. Gravity and distance
The Force of gravity decreases the further you move the two masses apart
The further you move away from the Earth the smaller the gravitational pull
you will feel and your weight will go down.
Warning: THERE is gravity in space
Watch this video
On zero gravity on
Earth

11. When will there be no resultant force on the spaceship?
Force
From
Moon
Force from Earth
1/6 mass of Earth

12. Apollo 13
1 5
2 3 4
Imagine you are a member of Apollo 13 describe your journey with respect to the
gravitational pull of the Earth and moon.