physics

Question 1

describe in the terms of molecules how thermal energy is transferred from the surface of the floor to the ceiling

Answer 1

air molecules gain kinetic energy from colliding with the surface of wood they vibrate colliding with neighbouring molecules transferring the energy so molecules move further apart
warmer air has lower density

Question 2

state the speed at which electromagnetic waves travel

Answer 2

3 x 10^8 m/s

Question 3

describe ways in which a longitudinal wave differs from a transverse wave

Answer 3

transverse waves vibrate at right angles from direction of wave travel
longitudinal wave vibrates parallel to the direction of the wave travel

Question 4

describe how sound waves are transmitted in air

Answer 4

longitudinal waves are parallel to the direction of wave propagation
vibration of air molecules forming compressions and rarefactions

Question 5

explain why the density of molten iron is lower than the density of solid iron

Answer 5

atoms in molten iron are further apart with larger spaces between them than solid iron so same mass occupies greater volume in liquid iron

Question 6

state the process in the sun that releases energy

Answer 6

nuclear fusion

Question 7

describe how nuclear fusion and fission differ

Answer 7

fusion is energy released by joining nuclei and in fission is energy released by splitting of nuclei