Science 2-2

Which of these is a measure of the average kinetic energy of the molecules of a material?

• bonding energy

• temperature

• heat

• thermal energy

A lizard sits on a hot rock to get warm. What type of thermal enrgy transfer is occurring?

• kinetic

• convection

• radiation

• conduction

What is thermal energy?

• the average kinetic energy in an object

• the average transfer of kinetic energy between two objects

• the total kinetic energy of an object

• the total transfer of kinetic energy between two objects

A hot potato at 80 degrees celsius is placed in a bowl of soup at 40 degrees celsius. The surrounding room is at 20 degrees celsius. What describes the directions of thermal energy transfer?

• potato to soup, and soup to room

• soup to potato, and potato to room

• room to soup, and soup to potato

• room to soup, and room to potato

Throughout the day, Matthew and Mei measured the temperature of lake water as it was warmed by the sun. The table shows their data at 4 different times.

At which time was the thermal energy of the lake water the greatest?

• 9 am

• 11 am

• 3 pm

• 5 pm

Four objects are all made of iron. Which has the most total thermal energy?

• a paper clip at 150 degrees celsius

• a nail at 100 degrees celsius

• a frying pan at 50 degrees celsius

• a spoon at 25 degrees celsius

Describe the scientific meaning of heat.

Answer explanation

Heat is the energy that is transfered between 2 objects that are at different temperatures.

When you touch a hot stove, heat is transferred from the stove to your hand because the stove has a higher temperature than your hand. 

If the temperature oustide increases from 30 degrees fahrenheit to 60 degrees fahrenheit, how has the kinetic energy of the air particles changed?

Answer explanation

The average kinetic energy of the air particles increases when the radiation waves warm up the air. The particles move faster because the temperature is increasing.

An ice cube floats in warm water in a container placed outside on a hot, sunny day. First, identify the processes by which the warm water contacting the ice cube AND the sun warming the air transfer energy.

Answer explanation

Direct contact transfers energy through CONDUCTION, so the warm water transfers energy to the ice cube through CONDUCTION. Radiation occurs when particles ABSORB energy that travels as a wave, so the sun warms the air through radiation.

An ice cube floats in warm water in a container placed outside on a hot, sunny day. Then, describe the direction of thermal energy flow. In other words, thermal energy is flowing from what substance to what substance?

Answer explanation

Thermal energy flows from the sun to the water. Then heat will flow from the water to the ice until the ice has completely melted and both substances have reached the same temperature.