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is helium more or less dense than water?
less dense 0.00018g/cm3
which of these is the unit of heat?
J oC N m3
J
What is the density of air?
0.0012g/cm3
Why can a thermos keep a hot drink warm for a long time?
A thermos reduces the loss of thermal energy, so heat does not leave the drink quickly.
Explain how sweat cools the skin.
Sweat evaporates from the skin. During evaporation, thermal energy is taken away from the skin, so the skin becomes cooler.
what is the formula for density?
mass divided by volume
Which of these is unit of temperature?
J oC N m3
oC
What is the density of water？
1.0cm3
Why does water need to keep moving through a car engine?
The moving water carries thermal energy away from the engine and helps prevent the engine from overheating.
Why does isopropanol feel cold when applied to the skin?
Isopropanol evaporates quickly. During evaporation, it takes thermal energy from the skin, making the skin feel cold.
vegetable oil,water with red ink,liquid soap,corn syrup and honey.Which liquid is denser?
honey
At what temperature is the spark approximately zuo?
1000oC
Thermal energy moves from __________ places to __________ places.
Thermal energy moves from hotter places to colder places.
When liquid water turns into gas, the water is said to __________.
When liquid water turns into gas, the water is said to evaporate.
a) Name the three methods of thermal energy transfer.
b) Which method can travel through a vacuum?
a) Conduction, convection, radiation
b) Radiation
What is the gas in carbonated drinks?
Carbon dioxide
1000J electrical energy splits into 500J kinetic energy and blank J thermal energy, how much becomes thermal energy?
500J
A cup of hot chocolate is left on a table for 15 minutes.Explain what will happen using the words “thermal energy”.
The hot chocolate will become cooler because thermal energy moves from the hot chocolate to the cooler air.
Hot water is left in a room.Which process also helps cool the water?
A. freezing
B. condensation
C. evaporation
D. boiling
C. evaporation
Tom wears a black T-shirt and Jack wears a white T-shirt on a sunny day.
a) Who will feel hotter?
b) Explain why.
a) Tom
b) Black absorbs more heat radiation from the Sun, while white reflects more radiation.
What is the density of carbon dioxide?
0.003g/cm3
100J electrical energy splits into 80J light and sound energy and blank J thermal energy, how much becomes thermal energy?
20J
A piece of hot metal is placed in cold water.Explain how thermal energy moves and what will happen in the end.
Thermal energy moves from the hot metal to the cold water.The metal becomes cooler and the water becomes warmer until they reach the same temperature.
What happens to the average energy of particles in a liquid during evaporation?
The average energy of the particles decreases because the particles with the most energy leave the liquid first.
A water tank has an electric heater at the bottom.
a) Explain why hot water rises to the top of the tank.
b) Why is hot water taken from the top instead of the bottom?
a) Hot water becomes less dense and rises by convection.
b) The hottest water collects at the top of the tank.