Question

Consider a 2-kg bowling ball sits on top of a building that is 40 meters tall. It falls to the ground. Think about the amounts of potential and kinetic energy the bowling ball has:

as sits on top of a building that is 40 meters tall.
as it is half way through a fall off a building that is 40 meters tall and travelling 19.8 meters per second.
as it is just about to hit the ground from a fall off a building that is 40 meters tall and travelling 28 meters per second.
When does the bowling ball have the most potential energy?

Question 1 options:

When it is sitting on top of the building.


When it is 1/2 down the building.


Just before it hits the ground.

Question 2 (1 point)
Directions: Consider a 2-kg bowling ball sits on top of a building that is 40 meters tall. It falls to the ground. Think about the amounts of potential and kinetic energy the bowling ball has:

Does the bowling ball have more potential energy or kinetic energy as it is half way through its fall?

Question 2 options:

The potential energy is the greatest.


The kinetic energy is the greatest.


The potential energy and kinetic energy are the same.

Question 3 (1 point)
Directions: Consider a 2-kg bowling ball sits on top of a building that is 40 meters tall. It falls to the ground. Think about the amounts of potential and kinetic energy the bowling ball has:

Does the bowling ball have more potential energy or kinetic energy just before it hits the ground?

Question 3 options:

This is when the kinetic energy is the greatest.


This is when the potential energy is the greatest.


The potential and kinetic energy are the same.

Question 4 (1 point)
What is the potential energy of the 2 kg ball that is sitting on top of the 40 meter building?

Question 4 options:

80 J


784 J


80 N


784 N

Question 5 (1 point)
The kinetic energy of the ball 1/2 way through the fall will be equal to 2kg*9.8*20 meters or 392 Joules, because the kinetic energy and potential energy are the same at this point.

Question 5 options:
True
False

Answer 1

1) At the highest point of the building.

2) The same amount of energy.

3) The kinetic energy is the greatest.

4) Potential energy = 784.8[J]

5) True

Step-by-step explanation:

Question 1

The moment when it has more potential energy is when the ball is at the highest point in the building, that is when the ball is at a height of 40 meters from the ground. It is taken as a point of reference of potential energy, the level of the soil, at this point of reference the potential energy is zero.

`E_(p) = m*g*h\\E_(p) = 2*9.81*40\\E_(p) = 784.8[J]`

Question 2)

The potential energy as the ball falls becomes kinetic energy, in order to be able to check this question we can calculate both energies with the input data.

`E_(p)=m*g*h\\ E_(p) = 2*9.81*20\\ E_(p) = 392.4[J]\\`

And the kinetic energy will be:

`E_(k)=0.5*m*v^(2)\\ where:\\v = velocity = 19.8[m/s]\\E_(k)=0.5*2*(19.8)^(2)\\ E_(k)=392.04[J]`

Therefore it is the ball has the same potential energy and kinetic energy as it is half way through its fall.

Question 3)

As the ball drops all potential energy is transformed into kinetic energy, therefore being close to the ground, the ball will have its maximum kinetic energy.

`E_(k)=E_(p)=m*g*h = 2*9.81*40\\ E_(k) = 784.8[J]\\ E_(k) = 0.5*2*(28)^(2)\\ E_(k) = 784 [J]`

Question 4)

It can be easily calculated using the following equation

`E_(p) =m*g*h\\E_(p)=2*9.81*40\\E_(p) =784.8[J]`

Question 5)

True

The potential energy at 20[m] is:

`E_(p)=2*9.81*20\\ E_(p)= 392.4[J]\\The kinetic energy is:\\E_(k)=0.5*2*(19.8)^(2) \\E_(k)=392[J]`