An elevator whose mass is m = 400 kilograms is supported by a cable. a frictional force of f = 80 newtons is applied to the elevator as it moves. determine the tension t in the cable when the elevator is:

a.) stationary;
b.) moving upward while accelerating at 2.8 m/s2;
c.) moving upward with a constant velocity-magnitude of 5 m/s;
d.) accelerating downward at 2.8 m/s2 with velocity downward;
e.) moving downward with a constant velocity-magnitude of 5 m/s.

3924 N

5124 N

4004 N

2884 N

4004 N

Explanation:

m = Mass of elevator = 400 kg

g = Acceleration due to gravity = 9.81 m/s²

a = Acceleration

f = Friction force = 80 N

When the elevator is stationary only the acceleration due to gravity will be acting on it

Tension

The tension is 3924 N

The balanced force equation would be

The tension is 5124 N

When velocity is constant acceleration is zero

The tension is 4004 N

The tension would be 2884 N

When velocity is constant acceleration is zero

The tension is 4004 N

d is the answer i came up with

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask