Power = (voltage) x (current)
(1,200 W) = (120 V) x (current)
Current = (1,200 watt) / (120 volt) = 10 Amperes.
How long the heater heats is irrelevant. The current
is flowing all the time, whenever the heater is running.
T = tension force in the rope in upward direction
m = mass of the box attached at end of rope = 56 kg
W = weight of the box in downward direction due to gravity
a = acceleration of the box in upward direction = 5.10 m/s²
weight of the box is given as
W = mg
inserting the values
W = (56) (9.8)
W = 548.8 N
force equation for the motion of the box is given as
T - W = ma
inserting the values
T - 548.8 = (56) (5.10)
T = 834.4 N
Answer:
(a) 0.81 V
(b) 0.52 V
Explanation:
Number of turns, N = 150
Radius, r = 2.5 cm = 0.025 m
Magnetic field, B = 0.060 T
f = 440 rev/min = 440 / 60 = 7.33 rps
A.
The maximum emf is given by
e = N x B x A x 2 x π x f
e = 150 x 0.060 x 3.14 x 0.025 x 0.025 x 2 x 3.14 x 7.33
e = 0.81 V
B.
The back emf is given by
e' = 2e / π = 2 x 0.81 / 3.14 = 0.52 V
