The Hot Chocolate Effect

The video explains the hot chocolate effect, where the frequency of sound increases over time when hot water is poured over instant coffee. It demonstrates how sound waves propagate in liquids and introduces the concept of bulk modulus, which measures a material's resistance to compression. The video compares different materials' bulk moduli and explains how mixing instant coffee with water affects the speed of sound propagation due to gas release. The conclusion presents an equation for frequency, highlighting the relationship between propagation speed and liquid height.

What happens to the frequency of sound when hot water is poured into a cup with dissolvable powder?

• It decreases over time.

• It remains constant.

• It increases over time.

• It fluctuates randomly.

What is the primary factor that changes when water and instant coffee mix, affecting the speed of sound propagation?

• Bulk modulus

• Density

• Viscosity

• Temperature

Which material has the highest bulk modulus among the following?

• Water

• Air

• Steel

• Diamond

What happens to the gas in the system when water is poured into instant coffee?

• It slowly escapes from the system.

• It remains trapped in the liquid.

• It dissolves completely.

• It reacts with the coffee.

What remains constant in the equation describing the frequency change in the hot chocolate effect?

• Bulk modulus

• Height of the liquid

• Density

• Speed of propagation