Answer:
5.69 m/s.
Explanation:
The given data is as follows.
Magnetic field strength (B) = 0.65 T
Speed (v) = 4.2 m/s
Induced emf (E) = ?
Formula for emf induced at the ends of the rod of length L which is moving with a speed of v is as follows.
E = BvL
Putting the given values into the formula as follows.
.
When magnetic field is changed to
Now, we assume that the speed be to get the emf
Then,
we can conclude that the speed v of the rod be adjusted to reestablish the emf induced between the ends of the rod at its initial value is 5.69 m/s.
Acceleration is -7 m/s²
Explanation:
initial velocity (u) = 14 m/s
since it's gonna stop,
final velocity (v) = 0m/s
time taken(t) = 2 seconds
now,
a = (v-u)/t
or, a = (0-14)/2
or, a = -14/2
a = -7m/s²
The answer is the the first one