In the EXPLORE section of your lesson 4.08 on Potential energy there were several animations to watch that provided a graphic illustrating how the PE and KE in a system changed as a skateboarder rides a halfpipe or a pendulum moves, why did the bar for the total energy remain constant? A
This is because no energy is being created or destroyed in this system
B Because these models do not take into account the impact of friction and air resistance and are helping to solidify the concept of energy conservation and that the total mechanical energy remains constant in that model.
C Energy is converted from kinetic to potential and potential to kinetic, but the total amount of energy is conserved.
D
all answers given are correct

This is because no energy is being created or destroyed in this system

Explanation:

I think this is correct? I hope it helps.        

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j

what's the