Answer:
Part a)

Part b)
Direction = upwards
Explanation:
When ball is dropped from height h = 4.0 m
then the speed of the ball just before it will strike the ground is given as



Now ball will rebound to height h = 2.00 m
so the velocity of ball just after it will rebound is given as



Part a)
Average acceleration is given as



Part B)
As we know that ball rebounds upwards after collision while before collision it is moving downwards
So the direction of the acceleration is vertically upwards
Answer:
The self-induced emf in this inductor is 4.68 mV.
Explanation:
The emf in the inductor is given by:

Where:
dI/dt: is the decreasing current's rate change = -18.0 mA/s (the minus sign is because the current is decreasing)
L: is the inductance = 0.260 H
So, the emf is:

Therefore, the self-induced emf in this inductor is 4.68 mV.
I hope it helps you!
Letter na that would be the answer