physics
posted by Anonymous .
A large fish hangs from a spring balance supported from the roof of an elevator.
If the elevator has an upward acceleration of 2.85m/s^2 and the balance reads 60.0N , what is the true weight of the fish?
Under what circumstances will the balance read 39.0N ?

True Weight of fish:
F= ma + mg
Where:
F=60.0N
a=2.85 m/s^s
g=9.80 m/s^2
Plug into formula where you are solving for m:
F = ma + mg
60.0 N = (2.85)m + (9.80)m
60.0 N = (12.65)m
m= 60.0N/12.65
m= 4.74 kg => 4740 g => 46.5 N
Under what circumstances will the balance read 39.0 N?
Formula: ∑F = F(normal) + F(weight)
Where:
∑F= a(4.74kg)
F(normal)= 39.0 N
F(weight)=(9.80m/s^2)(4.74kg)
Plug into formula:
∑F = F(normal) + F(weight)
a(4.74) = 39.0 N + (9.80)(4.74)
a(4.74) = 7.452
a = 1.57 m/s^2