A conducting rod moves perpendicularly through a uniform magnetic field. How does the emf change if the magnetic field is increa
1 answer:
Answer:
c) It increases by a factor of 8
Explanation:
According to Faraday's law (and Lenz' law), the induced EMF is given as the rate of change of magnetic flux.
Mathematically:
V = -dФ/dt
Magnetic flux, Ф, is given as:
Ф = BA
where B = magnetic field strength and A = Area of object
Hence, induced EMF becomes:
V = -d(BA)/dt or -BA/t
If the magnetic field is increased by a factor of 4, () and the time required for the rod to move is decreased by a factor of 2 (
), the induced EMF becomes:
The EMF has increased by a factor of 8.
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Answer:
Final Speed of Dwayne 'The Rock' Johnson = 15.812 m/s
Explanation:
Let's start out with finding the force acting downwards because of the mass of 'The Rock':
Dwayne 'The Rock' Johnson: 118kg x 9.81m/s = 1157.58 N
Now the problem also states that the kinetic friction of the desk in this problem is 370 N
Since the pulley is smooth, the weight of Dwayne Johnson being transferred fully, and pulls the desk with a force of 1157.58 N. The frictional force of the desk is resisting this motion by a force of 370 N. Subtracting both forces we get the resultant force on the desk to be: 1157.58 - 370 = 787.58 N
Now lets use F = ma to calculate for the acceleration of the desk:
787.58 = 63 x acceleration
acceleration = 12.501 m/s
Finally, we can use the motion equation:
here u = 0 m/s (since initial speed of the desk is 0)
a = 12.501 m/s
and s = 10 m
Solving this we get:
Since the desk and Mr. Dwayne Johnson are connected by a taught rope, they are travelling at the same speed. Thus, Dwayne also travels at 15.812 m/s when the desk reaches the window.