<u>Answer:</u>
Cannonball will be in flight before it hits the ground for 2.02 seconds
<u>Explanation:</u>
Initial height from ground = 20 meter.
We have equation of motion ,
, s is the displacement, u is the initial velocity, a is the acceleration and t is the time.
In this the velocity of body in vertical direction = 0 m/s, acceleration = 9.8
, we need to calculate time when s = 20 meter.
Substituting

So it will take 2.02 seconds to reach ground.
The period of the second pendulum is 0.9 s
Explanation:
The period of a simple pendulum is given by the equation

where
L is the length of the pendulum
g is the acceleration of gravity at the location of the pendulum
For the first pendulum, we have
L = 0.64 m
T = 1.2 s
Therefore we can find the value of g at that location:

Now we can find the period of the second pendulum at the same location, which is given by

where we have
L = 0.36 m (length of the second pendulum)

Substituting,

#LearnwithBrainly
Answer:
The mechanical energy of the helicopter is
.
Explanation:
It is given that,
Mass of the helicopter, m = 3250 kg
Speed of the helicopter, v = 56.9 m/s
Position of the helicopter, h = 185 m
The energy possessed by an object due to its motion is called its kinetic energy. It is given by :


The energy possessed by an object due to its position is called its potential energy. It is given by :


The sum of kinetic and potential energy is called mechanical energy of the system. It is given by :


or

So, the mechanical energy of the helicopter is
. Hence, this is the required solution.