Two particles A and B have mass 0.4 kg and 0.3 kg respectively - Edexcel - A-Level Maths Mechanics - Question 8 - 2010 - Paper 1

Using the value of acceleration from the previous calculations: $a = \frac{0.1g}{0.7} = 1.4 \, \text{m/s}^2$

Using the kinematic equation: $v = u + at$ Given that the initial velocity (u) is 0 and the time (t) is 0.5 s: $v = 0 + (1.4)(0.5) = 0.7 \, \text{m/s}$

Using another kinematic equation for distance (s): $s = ut + \frac{1}{2}at^2$ Substituting values gives: $s = 0(0.5) + \frac{1}{2}(1.4)(0.5)^2 = 0.175 \, \text{m}$

Using the equation again with u = 1 m (the height above the floor): $1 = 0.175 + \frac{1}{2}(9.8)t^2$

i.e. $1 - 0.175 = 4.9t^2$

Solving for t gives: $t = \sqrt{\frac{0.825}{4.9}} \approx 0.57 \, \text{s} \text{ or } 0.566 \, \text{s}$