Question

in order for nuclear fusion to occur, the core of the sun must be hot enough to overcome the __________ of the nuclei. doppler effect solar wind gravitational tides strong nuclear forces electromagnetic repulsions

Explanation:

Nuclear fusion requires high temperatures. Atomic nuclei are positively charged. Like charges repel (electromagnetic repulsion). High heat gives nuclei enough kinetic energy to overcome this repulsion.

• Doppler effect: related to wave frequency change (not fusion).
• Solar wind: stream of charged particles (not fusion barrier).
• Gravitational tides: due to gravitational forces (not fusion).
• Strong nuclear forces: attract at short range (help fusion, not barrier).

Answer:

electromagnetic repulsions