Page 166 - Physics

Physics for Secondary Schools

Syringe patient by pushing the
A syringe is a simple pump that consists of a plunger plunger.
that fi ts in a cylindrical tube, as shown in Figure 2. A syringe is used to
7.37. The plunger can be pulled and pushed inside measure or draw liquids
the tube or barrel. When the plunger is pulled out, the in a laboratory.
pressure inside the cylinder decreases; this makes the
atmospheric pressure higher than the pressure inside 3. A syringe is used to apply
the cylinder. Thus, the surrounding fl uid is pushed into certain compounds such
the syringe. When the plunger is pushed, the fl uid in as glue or lubricant.
the syringe is expelled since the pressure in the syringe
becomes higher than the atmospheric pressure. This Bicycle pump
enables the syringe to take in and expel fl uid through A bicycle pump is a type
the opening (nozzle) at the end of the tube. of force pump that consists
of a hollow metal cylinder

Plunger and a movable piston. It
is specifically designed
Barrel fl angre
for infl ating bicycle tyres.

Barrel The piston consists of a
Scale cup shaped leather washer
which is fi xed to a metal

Adapter rod by a metal washer, as
in Figure 7.38 (a).
Needle
When the piston is pulled
Bevel out, a low pressure is created
Figure 7.37: Syringe in the region just below the
leather washer. Atmospheric
Task 7.7
pressure then forces air into
Carefully observe the syringe and use it to take in the pump through the inlet
and expel different fl uids. Investigate and list down valve as in Figure 7.38 (b).
situations in our everyday life where the syringe is
used. When the piston is pushed

forward, the trapped
Uses of the syringe air below the piston is
The following are the uses of a syringe: compressed and the tube of
1. A syringe can be fi tted with hypodermic needles and the bicycle can be infl ated
used to administer injections. The injectable medicine using a valve as shown in
is expelled through the needle into the body of a Figure 7.38 (c).

160
Student’s Book Form One

Physics Form 1 Final.indd 160 16/10/2024 20:57