Page 66 - Physics

Physics for Secondary Schools

The body upon which the (a) Rigid
force acts is attached to support
the hook. The distance

through which the spring Spring
is stretched is directly
proportional to the
magnitude of the force Pointer
applied by the body. A
pointer is attached to the
spring and the magnitude Vertical force

of force is indicated on a
calibrated scale. The larger
the force, the more the Box
spring is stretched and the
higher the reading on the (b)
scale. The spring balance
can be used to measure Horizontal force
vertical and horizontal
forces acting on a body,

as shown in Figure 3.3 (a)
and (b). Figure 3.3: Spring balance used to measure forces

In Figure 3.3(a), the weight of the empty box is shown by the pointer on the spring
balance. If you weigh the same empty box fi lled with sand the pointer will indicate a
greater weight than that of the empty box. This is because the weight of sand adds to
the weight of the box. To get the weight of sand you need to subtract the weight of the
box from the weight of the empty box fi lled with sand.

Types of forces

Some forces in the environment occur naturally while others are derived from natural
forces. The naturally occurring forces are known as fundamental forces while the derived
forces are referred to as non-fundamental forces. The four fundamental forces are the
force of gravity, electromagnetic force, strong force, and weak force. All other forces
are derived from these fundamental forces. Examples of derived forces are elastic and
frictional forces. Depending on the interaction between objects, all forces can be classifi ed

as non-contact or action-at-a-distance forces and contact forces.

60
Student’s Book Form One

Physics Form 1 Final.indd 60 16/10/2024 20:56