SCIENCE FORM 2 CHAPTER 8 (8.2)

CHAPTER 8
FORCE AND MOTION

3

8.2 EFFECT OF
FORCE

2

Buoyant Force

The thrust force acting on an object that is
floating on the surface of a fluid.

 Actual weight: weight of an object in the
air

 Apparent weight: weight of an object
immersed in fluid

Buoyant force = actual weight – apparent
weight

Weight, W Weight, W Weight, W

Buoyant, B Buoyant, B Buoyant, B
+ve Buoyant Neural -ve Buoyant
Buoyant
FLOAT SINK
SUSPECTED

Example:

Scuba drivers use the buoyancy control to
help them sink or arise in water

Density of body = Density of water
 Achieve the neutral buoyancy

Example:

Cargo ships are marked with Plimsoll line for
safety purpose

Ship buoyancy change by temperature and
salt concentration in water

LEVER

A lever is :

 a bar that rotates on a fixed point.
 a simple machine.
 allows us to use minimal force to do work.

Force apply Object to
on the bar be move

Fixed support point

Purpose of a lever:

1. A lever allows us to do work easily.
2. A lever allows us to use minimal force to do work.

Classes of lever

First Class Lever

• In a first class lever , the Fulcrum is between the effort
and the load.

5pg

Second class lever

• In a and the effort. second lever , the Load is between the
fulcrum

6pg

Third Class Lever

• In a third class lever , the Effort is between the fulcrum
and the load.

7pg