Answer
given,
Weight of physics student, W = 550 N
combined mass of the student and elevator, M = 850
Apparent weight of the student when elevator start moving,N = 450 N
a) When apparent weight is Less than lift is moving downward.
m g - N = ma
N = m(g-a)
[tex]450 = \dfrac{550}{9.8}(9.8 -a)[/tex]
a = -1.78 m/s²
B) acceleration if scale reads 670 N
In this case lift move upward
N = m(g + a)
[tex]670 = \dfrac{550}{9.8}(9.8 +a)[/tex]
a = 2.14 m/s²
c) If the scale reads zero
acceleration of the elevator comes out to be
m (g + a) = 0
a = -9.8 m/s²
Hence, the elevator is in free fall.
d) Tension in case a)
T = m (g - a)
T = 850 x (9.81 - 1.78)
T = 6825.5 N
Tension in case c)
T = m (g - a)
T = 850 x (9.81 - 9.81)
T =0 N
