Question

a man weighing 60kg climbs up stair carrying a load of 20kg on his head . the stair case has 20 steps each of height 0.20m. if it takes 10s to climb find the power.

Answer 1

$we \: are \: given \: that \: \\ mass = 60 + 20 = 80kg \\ hieght = 20 \times 0.2 = 4m \\ and \: g = 10 \frac{m}{ {s}^{2} } \\ and \: time = 10sec$
$now$
$power \: = \frac{energy}{time}$
$power = \frac{mgh}{t}$
$now \: putting \: the \: values \: of \: mass \: m \\ \: height \: h \: and \: acceleration \: due \: to \\ gravity \: g \: and \: time \: t$
$power = \frac{80 \times 4 \times 10}{10}$
$power = 320 \: w$

Answer 2

Mass of man = 60kg

Mass of the man while he was climbing = 60+20= 80 kg

Height of the stair case = No. of steps × height of one step

= 20 × .20

= 4 m

g = 10m/S2

F = m× g ( acceleration due to gravity)

= 80 × 10

= 800 N

Workdone = Force × height

= 800 × 4

= 3200 Joule

T = 10 s

Power = Workdone / time

= 3200/10

= 320 Watt