Answer:
a) 3.65 seconds
b) 35.87 m/s
Explanation:
s = Displacement = 65.6 m
u = Initial velocity
v = Final velocity
t = Time taken
a = Acceleration due to gravity = 9.81 m/s² (downward direction is taken as positive and upward is taken as negative)
b) Equation of motion

Initial pop up velocity is 35.87 m/s
a)

It took 3.65 seconds to reach this height
Before the impact, let the velocity of the baseball was v m/s.
After being hit by the bat its velocity is -2v
So, change in velocity, Deltav=v-(-2v)=3v
Acceleration is defined as the rate of change in velocity, i.e. actual change in velocity divided by the time taken to change it. Time taken to change velocity is the time of actual contact of the bat and ball, i.e. 0.31 s.
a=(Deltav)/(Deltat)
=(3v)/0.37
Therefore, a/v=3/0.31=9.7 s^-1
So, the ratio of acceleration of the baseball to its original velocity is 9.7.
Answer:
External force on him will be 112 N
Explanation:
We have given the mass of the sprinter m =70 kg
Acceleration of the sprinter 
We have to find the net external force
According to second law of motion force = mass ×acceleration
Force is dependent on the mass and acceleration
So 
So external force will be 112 N
To solve this problem it is necessary to apply the concepts related to mutual inductance in a solenoid.
This definition is described in the following equation as,

Where,
permeability of free space
Number of turns in solenoid 1
Number of turns in solenoid 2
Cross sectional area of solenoid
l = Length of the solenoid
Part A )
Our values are given as,





Substituting,



PART B) Considering that many of the variables remain unchanged in the second solenoid, such as the increase in the radius or magnetic field, we can conclude that mutual inducantia will appear the same.