Question

An 80 kg man stands in a lift. calculate the force he exerts on a floor of the lift when the lift is

1- stationary

2- accelerating upward at 2 m/s^2

3- moving with a constant velocity (upward) at 4 m/s.​

Answer 1

Answer:

1- 800N

2- 960N

3- 800N

Explanation:

when lift is stationary force = wt. = m × g = 800N

when lift is accelerating upward at 2m/s²

net force on floor of lift = wt. + pseudo force

= 800 + ma

= 800 + 160 = 960N

but when lift is moving with constant velocity

net force = wt. of the man (bcoz net a = g)

Or you can see the fbd for second case to avoid the concept of pseudo force

Answer 2

Answers;784N ,

Explanation: