Physics
posted by Igbekele .
A boy whose mass is 40kg runs up a flight of 30 steps each 150mm high in 6seconds. Find the average power developed (take g as 10m/s^2.

work done = m g h = 40 * 9.81 * 30 * 0.150 Joules
power in Watts = work done / 6 seconds 
g=a=10m/s^2,
M=40kg,
S=150mm/1000=0.15m*30steps each=4.5m,
F=ma=40*10=400N
.'. Power=W/t=F*s/t=F*V=1800/6 = 300W Ans// or 0.3kW Ans// 
0.3kw