Physics cryptic 1

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Across
  1. 1. Berry onside said the composite but I'd got dropped (7)
  2. 5. Not unusual but always crosswise (6)
  3. 7. Somehow Cloe Caterina was inversely rad! (12)
  4. 12. Always conserved when given time before you headmistress (8)
  5. 13. Particular transfer due to temperature difference one by one (8)
  6. 15. The point you see Trotsky not a lepton (7)
  7. 17. Perhaps careful crone can only act over small distances (6)
  8. 18. Perth skirled somehow is law for planet harmony (7, 5)
  9. 20. Measured the object when in motion and found less. (6)
Down
  1. 2. About relative indefinite article church naturally (9)
  2. 3. Acid air vote about what to do with excess energy (11)
  3. 4. Spooner said shoe fon together (6)
  4. 6. Energetic Edwina ate bread back (4)
  5. 8. does not behave when resisting (8)
  6. 9. Describes the minimum energy required with this function (4)
  7. 10. VIP always never has to pay (6)
  8. 11. May this be with you by the time (7)
  9. 14. Help rope Roger hold the measurement when resting.
  10. 16. Apparently understand Dee (4)
  11. 19. Type of blue-green northern territory youth measure of all forms of the queen. (6)