Answer & Explanation:
Formula W = mg where gravitational field strength (g) is 9.81 (take g as 10 in O levels)
1. W = 2 x 9.81 = 19.62 = (20 N when g is 10)
2. W = (450/1000) x 9.81 = 4.4 N (4.5N when g is 10)
3. W = 0.75 x 9.81 = 7.35 N (7.5N when g is 10)
4. 75 = m x 9.81
m = 75/9.81
m = 7.64 N (7.5N when g is 10)
