[mahmoud khodary]

1 - a = 0.6 mls^2 w = 80 N
T = F = m * a m = w /g = 80 / 9.8 = 8.16 kg
T = 0.6 * 8.16 = 4.9 N

2 - m = 30 kg g = 10 m/s^2 W = m * g = 30 * 10 = 300 N

3 - m = 3 kg v = 5 m/s t = 2.5 s Ff = 7 N
a = v / t = 5 / 2.5 = 2 m/s^2
(F = Ff - m * a = 7 - (3 * 2
F = 1 N

4 - W = T = 15 N
W action
T reaction

5 - W = 7350 N a = 1 m/s^2 m = W/g = 7350/9.8 = 750 kg
F = m * a
F = 750 * 1 = 750 N