Answer:
The gravitational force on the elevator = 4500N
Explanation:
The given parameters are;
The force applied by the elevator, F = 4500 N
The acceleration of the elevator = Not accelerating
From Newton's third law of motion, the action of the cable force is equal to the reaction of the gravitational force on the elevator which is the weight, W and motion of the elevator as follows;
F = W + Mass of elevator × Acceleration of elevator
∴ F = W + Mass of elevator × 0 = W
F = 4500 N = W
The net force on the elevator is F - W = 0
The gravitational force on the elevator = W = 4500N.
Answer:
2.7 J
Explanation:
The energy of one photon is given by
where
h is the Planck constant
f is the frequency
For the photons in this problem,
So the energy of one photon is
The number of photons contained in 1.0 mol is
(Avogadro number)
So the total energy of 
photons contained in 1.0 mol is
By V=IR
A: 24=I*20
I = 1.2A
B: 220 = I*250
I = 0.88A
C: 6= I*3
I = 2 A
C,A,B
