PPT: Forces and Electricity | Year 6 Science IGCSE (Cambridge) - Class 6 PDF Download

 Page 1


Forces and 
Electricity
Page 2


Forces and 
Electricity
Mass and Weight
Mass
Mass is the amount of matter in an object, measured in kilograms 
(kg). In everyday English, we often use "weigh" and "weight" to refer 
to mass, which can be confusing.
The baby in the picture has a mass of 3.6 kg. This value remains 
constant regardless of location.
Weight
Weight is the amount of attraction on an object caused by gravity. 
It's the force exerted on our mass due to Earth's pull.
Scientists measure weight in newtons (N), named after Sir Isaac 
Newton, who first explained forces about 400 years ago in England.
Page 3


Forces and 
Electricity
Mass and Weight
Mass
Mass is the amount of matter in an object, measured in kilograms 
(kg). In everyday English, we often use "weigh" and "weight" to refer 
to mass, which can be confusing.
The baby in the picture has a mass of 3.6 kg. This value remains 
constant regardless of location.
Weight
Weight is the amount of attraction on an object caused by gravity. 
It's the force exerted on our mass due to Earth's pull.
Scientists measure weight in newtons (N), named after Sir Isaac 
Newton, who first explained forces about 400 years ago in England.
How does gravity affect 
weight?
Constant Mass
Objects have the same 
mass wherever they are. 
Your mass would be 
identical on Earth, the 
Moon, or Jupiter.
Variable Weight
Your weight changes 
depending on gravity. The 
smaller the gravitational 
force, the lower your 
weight will be.
Gravitational Differences
The Moon's gravitational force is less than Earth's because 
the Moon has a smaller mass. On the Moon, you would 
weigh less, even though your mass remains unchanged!
Page 4


Forces and 
Electricity
Mass and Weight
Mass
Mass is the amount of matter in an object, measured in kilograms 
(kg). In everyday English, we often use "weigh" and "weight" to refer 
to mass, which can be confusing.
The baby in the picture has a mass of 3.6 kg. This value remains 
constant regardless of location.
Weight
Weight is the amount of attraction on an object caused by gravity. 
It's the force exerted on our mass due to Earth's pull.
Scientists measure weight in newtons (N), named after Sir Isaac 
Newton, who first explained forces about 400 years ago in England.
How does gravity affect 
weight?
Constant Mass
Objects have the same 
mass wherever they are. 
Your mass would be 
identical on Earth, the 
Moon, or Jupiter.
Variable Weight
Your weight changes 
depending on gravity. The 
smaller the gravitational 
force, the lower your 
weight will be.
Gravitational Differences
The Moon's gravitational force is less than Earth's because 
the Moon has a smaller mass. On the Moon, you would 
weigh less, even though your mass remains unchanged!
Measuring Mass and 
Weight
Measuring Mass
We measure mass in 
grams and kilograms 
using a measuring scale. 
For example, when 
baking a cake, you 
measure the mass of 
flour, sugar, and butter in 
grams.
Measuring Weight
We measure weight in 
Newtons using a 
forcemeter. The 
forcemeter hangs by a 
hook and has another 
hook at the opposite end 
to hang the object being 
measured.
Page 5


Forces and 
Electricity
Mass and Weight
Mass
Mass is the amount of matter in an object, measured in kilograms 
(kg). In everyday English, we often use "weigh" and "weight" to refer 
to mass, which can be confusing.
The baby in the picture has a mass of 3.6 kg. This value remains 
constant regardless of location.
Weight
Weight is the amount of attraction on an object caused by gravity. 
It's the force exerted on our mass due to Earth's pull.
Scientists measure weight in newtons (N), named after Sir Isaac 
Newton, who first explained forces about 400 years ago in England.
How does gravity affect 
weight?
Constant Mass
Objects have the same 
mass wherever they are. 
Your mass would be 
identical on Earth, the 
Moon, or Jupiter.
Variable Weight
Your weight changes 
depending on gravity. The 
smaller the gravitational 
force, the lower your 
weight will be.
Gravitational Differences
The Moon's gravitational force is less than Earth's because 
the Moon has a smaller mass. On the Moon, you would 
weigh less, even though your mass remains unchanged!
Measuring Mass and 
Weight
Measuring Mass
We measure mass in 
grams and kilograms 
using a measuring scale. 
For example, when 
baking a cake, you 
measure the mass of 
flour, sugar, and butter in 
grams.
Measuring Weight
We measure weight in 
Newtons using a 
forcemeter. The 
forcemeter hangs by a 
hook and has another 
hook at the opposite end 
to hang the object being 
measured.
Weightlessness
Zero Gravity in Space
The International Space 
Station orbits Earth in a 
state where forward 
motion equals the speed 
of "falling" toward Earth, 
creating weightlessness 
for astronauts inside.
Physical Effects
Weightlessness affects 
multiple body systems. 
Astronauts lose calcium 
from bones, muscles 
weaken, and their sense 
of "up and down" 
becomes confused.
Counter measures
Astronauts must exercise two hours daily to combat these 
effects. Even with exercise, a six-month mission requires 
several months of rehabilitation upon return to Earth.