Chapter 2 - Kinematics: Description of Motion - Learning Path Questions and Exercises - Exercises - Page 64: 74

$a). 14m/s$ $b). 8.85m/s$ $c). 2.33s$

a). $v^{2}=u^{2}+2aS$ $v^{2}=0+2\times 9.8 \times 10$ $v=14m/s$ b). $0=u^{2}-2\times 9.8\times 4$ $u=8.85m/s$ c). $S=ut+\frac{1}{2}at^{2}$ So, $10=0+0.5\times 9.8\times t^{2}$ $t=1.43s$ Also, $4=0+0.5\times 9.8\times t^{2}$ $t=0.9s$ Total time $=2.33s$