For all antinodal positions we know that

now we also know the relation between phase difference and path difference

now we will have

now from above equation we will have

now for the first anti node position
N = 1

Option D is correct
Answer:
The energy that the truck lose to air resistance per hour is 87.47MJ
Explanation:
To solve this exercise it is necessary to compile the concepts of kinetic energy because of the drag force given in aerodynamic bodies. According to the theory we know that the drag force is defined by

Our values are:




Replacing,


We need calculate now the energy lost through a time T, then,

But we know that d is equal to

Where
v is the velocity and t the time. However the time is given in seconds but for this problem we need the time in hours, so,

(per hour)
Therefore the energy that the truck lose to air resistance per hour is 87.47MJ
Answer:
3,237.78N
Explanation:
According to Newton's second law of motion
F = mass * acceleration
Since a = v-u/t
F = m(v-u)/t
Given
Mass m = 0.155kg
v = 50.0m/s
u = -44.0m/s
Time t = 0.00450secs
Substitute
F = 0.155(50-(-44))/0.00450
F = 0.155(50+44)/0.00450
F = 0.155(94)/0.00450
F = 14.57/0.00450
F = 3,237.78N
hence he hit the baseball with a force of 3,237.78N