If planetesimal impacts were fewer what would be the effect on Earth's early heat?

Correct answer: A major source of early heat would decrease

When planetesimals struck the early Earth, their kinetic and gravitational energy was converted into heat. Therefore, fewer impacts would reduce a major source of Earth's early heat. Radioactive decay was a separate source of internal heat and would not stop simply because impacts became fewer. Exam tip: remember planetesimal impacts, gravitational compression, and radioactive decay as key sources of Earth's early heat.