Physics - Kinematics Question with Solution | TestHub

(i) $\mathrm{v}=\mathrm{u}+$ at ${}_1$ $$\begin{array}{l}40=0+a\times 20\\ a=2m/s^2\\ v^2-u^2=2as\\ 40^2-0=2\times 2s_1\\ \text{ (ii) }{s}_1=400\mathrm{m}\\ \text{ (iii) }v=u+at\\ 0=40+a\times 40\\ a=-1\mathrm{m}/{\mathrm{s}}^2\\ 0^2-40^2=2(-1){\mathrm{s}}_3\\ {\mathrm{s}}_3=800\mathrm{m}\\ \text{ Total distance travelled }={\mathrm{s}}_1+{\mathrm{s}}_2+{\mathrm{s}}_3\\ =400+800+800=2000\mathrm{m}\\ \text{ Total time taken }=20+20+40=80\mathrm{s}\\ \text{ Average velocity }=\frac{2000}{80}=25\mathrm{m}/\mathrm{s}\end{array}$$