Mphamvu yachibadwa ndi mphamvu yomwe imagwira ntchito pazinthu zomwe zakhudzana, komwe komwe mphamvuyo ikupita ndi mzere wolunjika ku malo olumikizirana. Chizindikiro chake ndi N ndipo dongosolo lapadziko lonse la mayunitsi ndi kg m/s 2 kapena Newton.
Kanikizani N pamalo osalala
N ndi mphamvu yochokera pansi pa mtengo, N' ndi mphamvu yochokera pansi pa mtengo. w ndi mphamvu yokoka yomwe imagwira ntchito pa mtengo kapena kulemera kwa mtengowo. N ndi N' ndi mphamvu zochitira zinthu, pomwe N ndi w si mphamvu zochitira zinthu.
Ngati chipikacho chili pamalo opumulira kapena sichikuyenda molunjika, kukula kwa mphamvu N kungawerengedwe pogwiritsa ntchito lamulo loyamba la Newton.
ΣF y = 0
N – w = 0
N = w
Ngati chipikacho chakankhidwira pansi ndi mphamvu F monga momwe zilili pachithunzi chomwe chili m'mbali, ndiye kuti kukula kwa mphamvu N ndi:
ΣF y = 0
N – w – F = 0
N = w + F
Mphamvu yachibadwa pa ndege yopendekeka
N ndi N' ndi mphamvu zochitira zinthu. N ndi mphamvu yachibadwa yomwe imagwira ntchito pa boloko ndipo N' ndi mphamvu yachibadwa yomwe imagwira ntchito pa boloko lopendekeka. W ndi gawo loyima la mphamvu yokoka (w). Mphamvu yokoka (w) imagwira ntchito pa boloko. Kukula kwa mphamvu yachibadwa ndi
ΣF y = 0
N – w y = 0
N = w y = w cos theta
