2.A girl of mass 50kg climbs a flight of a stair having 40steps each of 30m high in 10 s. Calculate the power developed by the girl.

force → (50 × 10) = 500 Ndistance → (30 × 40) = 1200 mtime → 10 seconds

Answer: it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.explanation:   we have equation of motion ,where s is the displacement, a is the acceleration, u is the initial velocity and t is the time taken.average velocity = displacement/ time taken.average velocity = 10.69 miles/hr = 10.69*1.6*1000/(60*60) = 4.75 m/s4.75 = s/ts = 4. 1we also have acceleration = 2.18 m/s², initial velocity = 0 m/sso it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.