For this case, in the next item we have gravitational potential energy:
An apple in a tree.
Suppose we define our reference system at the floor level.
Suppose the apple is at a height h from the floor and has mass m.
The gravitational potential energy of the apple is given by:
U = mgh
Where,
m: apple mass
h: height of the apple with respect to the floor
g: acceleration due to gravity
Answer:
C) an apple on a tree
Answer:
Moment of inertia of the system is 289.088 kg.m^2
Explanation:
Given:
Mass of the platform which is a uniform disk = 129 kg
Radius of the disk rotating about vertical axis = 1.61 m
Mass of the person standing on platform = 65.7 kg
Distance from the center of platform = 1.07 m
Mass of the dog on the platform = 27.3 kg
Distance from center of platform = 1.31 m
We have to calculate the moment of inertia.
Formula:
MOI of disk = 
Moment of inertia of the person and the dog will be mr^2.
Where m and r are different for both the bodies.
So,
Moment of inertia
of the system with respect to the axis yy.
⇒ 
⇒ 
⇒ 
⇒
The moment of inertia of the system is 289.088 kg.m^2
The equivalent resistance of n resistors connected in parallel is given by

(1)
In our problem, the resulting resistance of the 5 pieces connected in parallel is

, and since the 5 pieces are identical, their resistance R is identical, so we can rewrite (1) as

From which we find

.
So, each piece of wire has a resistance of

. Before the wire was cut, the five pieces were connected as they were in series. The equivalent resistance of a series of n resistors is given by

So if we apply it at our case, we have

therefore, the resistance of the original wire was

.
Answer: h = 3R
Explanation:
Using the law of conservation of energy,
Total energy at the beginning of the launch would be equal to total energy at any point.
kinetic energy + gravitational potential energy = constant
Initial energy of the projectile =
... (1)
where R is the radius of the Earth, M is the mass ofthe Earth, m is the mass of the projectile.
escape velocity, 
Total energy at height h above the Earth where speed of the projectile is half the escape velocity:
...(2)
(1)=(2)
⇒
⇒
⇒
⇒
⇒h = 3R
Thus, at height equal to thrice radius of Earth, the speed of the projectile would reduce to half of escape velocity.
Answer:
the sample is approximately 4065 years old