Force and Pressure

1
Force and Pressure
1
2
What are Forces?

• A push or pull

3
Examples of Forces

• Squeezing
• Stretching
• Twisting
• Folding

4
Effects of Forces

• Objects shape changes
• Objects size changes
• Stationary object moves

5
Effects of Forces

• Moving object stops
• Moving object speeds up or slows down
• Direction of an objects motion changes

6
Weighing scale
7
Tsunami
8
Weight lifting
9
Ultimate frisbee
10
Naruto vs Sasuke
11
Measuring Forces

• S.I unit of force is newton (N)
• Spring balance used to measure the amount of
  force applied

12
Types of Spring Balance

• Extension spring balance
• Spring stretches when a pulling force acts on it
• Greater force, greater extension
• Spring attached to a pointer which indicates the
  amount of force exerted on the spring

13
Types of Spring Balance

• Compression spring balance
• Spring compressed when a pushing force acts on it
• Greater force, greater compression
• Spring attached to a pointer which indicates the
  amount of force exerted on the spring

14
Forces Around Us

• Gravity
• Friction
• Magnetism

15
Gravity

• Gravity is the force that attracts objects to the
  Earth
• Mass is a measure of the amount of matter in a
  body
• Weight is a measure of the gravitational force
  exerted on the object

16
Friction

• Frictional force acts when one materials rubs
  against another
• Friction is useful in walking and when applying
  brakes to stop a car
• Constant friction leads to wear and tear
• Friction produces heat

17
Magnetism

• Magnetism is the force exerted by a magnet on
  magnetic materials such as iron and steel
• Every magnet has a North pole and a South pole
• Like poles repel
• Unlike poles attract

18
What is Pressure?

• Amount of force
• acting on a unit area
• A sharp object pierces a surface more easily than
  a blunt object

19
Calculating Pressure
Force

• Pressure

Area
20
Applications of Pressure in Everyday Life

• Bulldozer
• Can openers
• Knife
• Plane
• Suction cups