Question

An object initially at rest falls from a height H until it reaches the ground. Two of the following energy bar charts represent the kinetic energy K and gravitational potential energy Ug of the object-Earth system at two positions. The first position is when the object is initially released, and the second position is when the object is halfway between its release point and the ground. Which two charts could represent the mechanical energy of the object-Earth system? Select two answers. by Ug K Ug к Mechanical Energy at Halfway Point Mechanical Energy at Release Point Mechanical Energy at Release Point Mechanical Energy at Halfway Point d. c. к Ug Ug K Mechanical Energy at Release Point Mechanical Energy at Halfway Point Mechanical Energy at Release Point Mechanical Energy at Halfway Point

Answer 1

Answer: B&C

Step-by-step explanation:

Release point: Ug bar graph only K none

Halfway point: Ug and K are equal bar graph

second option,

Release point: empty graph

Halfway point: Ug down half K up half

Answer 2

Initial: bar power U₀

Final: bar power U = U₀ / 2

bar Kinetic energy K = U₀ / 2

These two bars are half the height of the initial bar

Step-by-step explanation:

To know which graph is correct, let's discuss the solution to the problem

Initial mechanical energy

Em₀ = U₀ = m g H

The mechanical energy at the midpoint

Em₂ = K + U₂

As there is no friction, mechanical energy is conserved

Em₀ = Em₂

U₀ = K + U₂

K = U₀ - U₂

K = m g (H - y₂)

Indicates that position 2 corresponds to y₂ = H / 2

K = m g (H –H / 2)

K = ½ m g H

K = ½ Uo

Therefore the graph must be

Initial: bar power U₀

Final: bar power U = U₀ / 2

bar Kinetic energy K = U₀ / 2

These two bars are half the height of the initial bar