m = 70 kg
10 m/s2 = g
In each scenario, the weighing machine measures the response R, or apparent weight.
(a) The lift’s acceleration equals 0 when it travels upwards at a uniform speed of 10 m/s.
R = mg = 70 x 10 = 700 N
(b) Lift with a = 5 ms-2 going downhill
The equation of motion may be expressed as using Newton’s second law of motion:
Mass of the man, m = 70 kg,
g = 10 m/s2
The weighing machine in each case measures the reaction R, i.e., the apparent weight.
(a) When the lift moves upwards with a uniform speed of 10 m/s, it’s acceleration= 0.
R = mg = 70 x 10 = 700 N
(b) Lift moving downwards with a = 5 ms-2
Using Newton’s second law of motion, the equation of motion can be written as
R+mg = ma
R = m (g – a) = 70 (10 – 5) = 350 N
c) Lift with a = 5 ms-2 going upwards
R = m (g + a) = 70 (10 + 5) = 1050 N
(d) Downward if the lift were to fall freely due to gravity. g = a
R = m(g – g) = m(g – g) = 0
The man will experience weightlessness.