HKDSE Physics Question Review (20240825)

1. Explain why ice is a poor conductor of heat.

2. Using 4 approaches, explain why a cockroach always runs faster than an elephant.

Solution:

1. A solid has lower latent heat than a gas, so ice has low internal energy and the molecules are virtually immobile. With low Kinetic energy, the seas under the ice layers on the surface seldom solidify.

2.

Method 1:

A cockroach has 6 legs while an elephant has only 4 legs, so the former must accelerate faster.

Method 2:

An elephant has greater mass so in a motion, the elephant must experience greater static friction to overcome.

Method 3:

Given F=ma, when force is a constant, those with greater mass must accelerate slower.

Method 4:

The surface area to volume ratio for a cockroach is faster. This means that the coxkroach must lose more energy to heat as it respire more. This is manifested by the motion powered by the muscles of the cockroach.

The surface area to volume ratio for a cockroach is greater.

Bonus Question:

Explain how the velocity of light is derived.

This means that the cockroach must lose more energy to heat as it respires more

Note: Latent heat is a measure of potential energy of molecules. When the distance between molecules increase, the internal energy will increase, given constant translational Kinetic energy and rotational Kinetic energy.

HKALE gets imbecile since 1985.