Question

A 60 kg student does 60 push ups in 40s . With each push up , the student must lift 70% of the body mass a height of 40cm off the floor. Assuming two significant digits, calculate the following

The work the student does against a force of gravity for each push up , assuming work is done only when the student pushes up

The total work done against the force of gravity in 40s

The power achieved for this period

Answer 1

(60 kg)(9.8 m/S^2) = Force in Newton

Answer 2

m g * .40 = 60 * 9.8 * .7 = 412 Newtons force

distance up = .40 meters

work per push up = .40*412 = 165 Joules per push up
total work = 165 * 60 = 9878 Joules

power = work/time = 9878/40 = 247 watts

Answer 3

a)1.6 x 10^2
b) 9.6 x 10^3
c) 240W