Answer:
Part a)
When rotated about the mid point

Part b)
When rotated about its one end

Explanation:
As we know that the angular acceleration of the rod is rate of change in angular speed
so we will have



Part a)
When rotated about the mid point



now torque is given as


Part b)
When rotated about its one end



now torque is given as


Some thing that is done physically like with a persons hands and such
Answer:
W = 47040 J
Explanation:
Given that,
The mass of a student, m = 60 kg
Height of the tower, h = 80 m
We need to find the work done in climbing the tower. The work done is given by :
W = mgh
So,
W = 60 × 9.8 × 80
W = 47040 J
So, the required work done is 47040 J.
Answer:
6.5 m above the floor and 5 m above Christine's hand when it reaches the maximum height.
Explanation:
Let g = 10 m/s2 be the gravitational deceleration that affects the ball vertical motion so it comes to the maximum height at 0 speed. We can use the following equation of motion to find out the distance traveled by the ball from where it's thrown:

where v = 0 m/s is the final velocity of the ball when it reaches maximum level,
= 10m/s is the initial velocity of the ball when it starts, g = -10 m/s2 is the deceleration, and
is the distance traveled, which we care looking for:


So the ball is 5 m above Christine' hands when it reaches maximum height, and since the hand is 1.5 m above the floor, the ball is 5 + 1.5 = 6.5 m above the floor when it reaches maximum height.