X = V0 t + 0.5 a t 2
50 = 0 + 0.5 × a × 25
a = 500 ÷ 125 = 4 m /s 2
F = m a = 30 × 4 = 120 N ..................(1)
Vt 2 = V0 2 + 2 X a
100 = 400 + 2 × 25 × a
a = 2 - 8 = - 6 m /S 2
F = m a = 30 × -6 = - 180 N ....................(2)
هي قوة مقدارها 180 نيوتن عكس اتجاه الحركة
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